DEV Community: Saras Growth Space

Fridge2Feast: What Can You Cook With What You Already Have?

Saras Growth Space — Fri, 16 Oct 2026 15:55:03 +0000

This is a submission for the Hacktoberfest Open-Source AI Challenge Week 2: Side Hustle

The Problem: A Fridge Full of Ingredients, but Nothing to Cook

We've all been there.

You open the fridge and find two tomatoes, half an onion, some leftover rice, a few vegetables, and perhaps a container of something you bought three days ago.

There is food in the kitchen. But somehow, there is nothing to cook.

You search for recipes online. The first recipe needs cream. The second needs a special sauce. The third requires ingredients you don't have.

And before you know it, you're considering ordering food again.

What if you could simply list the ingredients you already have and discover what you can make with them?

That is the idea behind Fridge2Feast.

What Is Fridge2Feast?

Fridge2Feast is a proposed AI-powered cooking assistant that turns an everyday ingredient list into practical meal ideas.

The goal isn't to generate the most impressive recipe. It's to help people make the best use of the food they already have.

Imagine entering:

Potatoes
Tomatoes
Onions
Spinach
Leftover rice
Basic Indian spices

Instead of suggesting an elaborate recipe with a long shopping list, the assistant would prioritize realistic options based on those ingredients.

Depending on the quantities and available pantry staples, suggestions might include a simple potato-and-spinach curry, a tomato-based vegetable dish, or a quick fried-rice variation.

Each suggestion would explain which ingredients are required, which are optional, what substitutions might work, and what additional items—if any—are needed.

The idea is simple: start with the ingredients, not the recipe.

Who Is It For?

Fridge2Feast could be useful for several groups.

Students and people living alone who want affordable meals without buying ingredients they will use only once.

Busy households that need to turn leftover ingredients into another meal.

Budget-conscious cooks who want to make better use of their groceries.

People learning to cook who have ingredients available but don't yet know how to combine them.

For these users, the value isn't another collection of recipes. It's making the next cooking decision easier.

How Would It Work?

The proposed experience would have four steps.

1. Enter what you have

Users could type a list of ingredients, such as:

"Two potatoes, one onion, tomatoes, spinach, leftover rice."

A future version could also accept a photograph of the fridge, although recognizing ingredients accurately from images would require additional testing.

2. Find realistic combinations

An open-weight language model could interpret ingredient names, understand common substitutions, and generate candidate dishes.

A separate ingredient-matching layer would check how closely each recipe fits what the user has available.

Recipes that require fewer additional ingredients would be prioritized.

3. Show useful, honest suggestions

Each dish could include:

Ingredients available and ingredients missing
Estimated preparation time
Simple cooking instructions
Optional substitutions
A clear distinction between essential and optional ingredients

The assistant should never pretend that a recipe is fully achievable when a necessary ingredient is missing.

4. Help use food before it goes to waste

Users could optionally mark ingredients they want to use soon.

The system could prioritize suitable recipes around those ingredients, while reminding users that appearance or an AI-generated suggestion cannot reliably establish whether food is safe to eat.

Why Open-Source AI?

For Fridge2Feast, open innovation could offer more than an alternative model provider.

Local processing and privacy

A locally running open-weight model could process ingredient lists without sending them to a third-party AI API.

This could be useful for people who prefer to keep their household routines and food preferences private.

Actual offline operation would depend on downloading the model and all required assets in advance.

Adaptation to local cooking

Food isn't universal.

An ingredient combination that works in one cuisine may be unusual in another. A useful assistant should understand familiar dishes, regional ingredient names, common pantry staples, and practical substitutions.

An open model could be evaluated, prompted, or fine-tuned for these needs, subject to its license and available hardware.

More predictable operating costs

A small model running on a user's own device could reduce recurring inference costs and avoid dependence on a paid API for every recipe request.

Local inference would still have hardware, electricity, and maintenance costs. The objective would be to make the economics more sustainable, not to pretend that running AI is entirely free.

Freedom to improve the system

The model could be changed as better options become available. Recipe matching, dietary preferences, and food-safety constraints could be handled by explicit application logic instead of relying entirely on generated text.

That combination of adaptable models and inspectable rules is central to the proposed design.

Could This Become a Side Hustle?

The potential customers are people who cook regularly and want to save time, money, or food.

A possible business model would be a free basic ingredient-to-recipe experience, with a paid tier for features such as weekly meal planning, household profiles, pantry tracking, and shopping-list generation.

Another possibility would be a low-cost product for shared households or budget-conscious meal planners.

These are hypotheses, not validated business results. Before charging anyone, the concept would need to be tested with real users to understand which features they value enough to pay for.

What I Would Build First

Rather than starting with a complicated application, the first prototype would focus on one job:

Accept an ingredient list.
Suggest three suitable dishes.
Show missing ingredients honestly.
Provide simple instructions.
Prioritize using available ingredients.

The prototype could use a small open-weight model through a local inference runtime, supported by structured ingredient matching and basic cooking constraints.

The next step would be to compare its suggestions against a conventional recipe-search workflow and ask home cooks whether it actually helps them prepare meals more easily.

This is currently a project concept, not a completed application. No working demo, user testing, or revenue is being claimed.

The Bigger Idea

We often think of AI as a way to create more content, more options, and more things to consume.

But sometimes the useful answer is much simpler.

You don't need another grocery order. You don't need another recipe requiring ten unfamiliar ingredients. You might already have enough to make a good meal.

What if AI helped us make better use of what we already have?

That's the question behind Fridge2Feast: less food waste, fewer unnecessary purchases, and a practical path from a list of ingredients to dinner.

What If the Sounds of Our Childhood Could Bring Us Back Outside?

Saras Growth Space — Mon, 12 Oct 2026 03:51:05 +0000

This is a submission for the Hacktoberfest Open-Source AI Challenge Week 1: Touch Grass

The Idea: Nostalgia as a Reason to Step Outside

Do you remember the sound of children playing outside in the evening?

The distant sound of a ball hitting the ground. Someone calling a friend home. Birds returning to the trees. Leaves moving in the wind. The familiar, unplanned noise of a neighborhood that seemed to come alive as the day slowed down.

For many of us, these sounds belong to a childhood when going outside wasn't something we had to schedule. We simply stepped out.

Today, we can spend hours surrounded by digital content while feeling strangely disconnected from the world outside our windows.

What if, instead of sending another notification that says "Go touch grass," we used the sounds associated with our happiest outdoor memories to encourage us to do just that?

That is the idea behind Echoes of Yesterday.

It is a concept for a nostalgia-inspired, AI-assisted experience designed to help people reconnect with the outdoors through familiar environmental sounds.

What Is Echoes of Yesterday?

The idea is simple: choose a memory, listen to a short soundscape, and let that experience become an invitation to step outside.

Imagine opening the experience and choosing:

An evening from childhood: Children playing, distant conversations, a ball bouncing, and the atmosphere of a neighborhood at dusk.
A quiet afternoon: Birds chirping, a soft breeze, rustling leaves, and the occasional sound of life nearby.
A rainy day: Raindrops on the ground, water flowing along a street, and the gentle ambience of a familiar rainy afternoon.
A summer holiday: Crickets, trees moving in the wind, distant laughter, and the feeling of a long, unhurried day.

These would not be recordings of a user's actual past. They would be carefully composed soundscapes inspired by the kinds of experiences people remember.

The goal would not be to keep someone listening to a screen for twenty minutes.

It would be to create a small moment of recognition, then encourage them to experience the real world around them.

The screen starts the experience. The world outside completes it.

How Would It Work?

The proposed experience would have three simple stages.

1. Choose a feeling or memory

Instead of asking users to write a long prompt, the experience could offer simple choices:

The neighborhood where I grew up
Playing outside until sunset
Rainy afternoons
A garden or a field
Quiet mornings filled with birdsong

Users could also describe a memory in their own words.

2. Let open-source AI compose a soundscape

An open-weight language model running locally could interpret the user's description and convert it into a structured soundscape plan.

For example, a memory of playing outside at sunset might become a sequence of environmental sounds, with children playing in the distance, a few birds, a gentle breeze, and the gradual quiet of evening.

The soundscape could be assembled from appropriately licensed audio recordings rather than relying on a closed, cloud-based AI service to generate everything.

The model would decide how the elements fit together; the audio assets would provide the actual sounds.

3. Take the experience outside

After a short listening session, the experience could offer one gentle invitation:

Step outside for five minutes. Notice the sounds that are already there.

No endless feed. No streaks to maintain. No pressure to turn relaxation into another productivity goal.

Just a small bridge between a remembered world and the one that still exists around us.

Why Open-Source AI?

For this idea, open innovation would not simply be a technical preference. It could shape the experience itself.

Personalization without sending memories to a server

Childhood memories can be deeply personal. A locally running model could interpret a memory description on the user's device, without requiring that description to be sent to a third-party AI API.

That would make privacy a design choice rather than an afterthought, provided the eventual implementation keeps processing and storage local.

The freedom to change the model

An open-weight model could be replaced with another model that performs better at understanding short descriptions, producing structured outputs, or running on modest hardware.

The experience would not need to be permanently tied to one provider's API, pricing, or model behavior.

A potentially offline experience

If the model and licensed audio assets were downloaded in advance, the core experience could eventually work without an internet connection.

Someone sitting in a garden, visiting a park, or walking along a quiet path would not need a continuous connection to a cloud service.

More control over the experience

The project could use a small, constrained model prompt and a predefined sound library rather than giving an AI unrestricted control over the experience.

This would make the output easier to inspect, customize, and reproduce.

Open-source components would not automatically make the experience free, private, or offline. Those properties would depend on the selected model's license, hardware requirements, audio licenses, and implementation. But open technology would give the project more room to make those choices deliberately.

Why This Fits the Touch Grass Theme

Many digital products compete for our attention by giving us more to watch, read, or listen to.

Echoes of Yesterday would explore the opposite direction.

Could technology help us remember the pleasure of being outside, then give us a reason to put the device away?

The experience would be deliberately short. Its success would not be measured by session length or the number of times someone opens the app. A more meaningful outcome would be whether someone actually steps outside, notices their surroundings, or spends a few quiet minutes away from a screen.

The soundscape is the invitation, not the destination.

What I Would Like to Explore Next

This is currently a project concept, not a completed or tested application.

The next steps would be to identify a suitable open-weight model, assemble a small collection of properly licensed environmental recordings, and build a minimal prototype that turns a memory description into a playable soundscape.

I would also want to test the idea with real people. Do familiar environmental sounds genuinely make someone more inclined to go outside, or do they simply provide another enjoyable digital experience?

That distinction matters.

Nostalgia should be an invitation to engage with life, not a substitute for it.

One Last Thought

We often use technology to create something new for ourselves.

Perhaps sometimes it can help us rediscover something we already know.

The sound of children playing outside. Wind moving through trees. Birds calling from somewhere nearby. The ordinary sounds of a world that existed before every quiet moment needed a screen to fill it.

What if the best use of AI were not to keep us online longer, but to help us remember why we want to go outside in the first place?

That is the possibility I would like to explore with Echoes of Yesterday.

This is an early-stage concept. No working application, demo, or real-world user testing is being claimed in this article.

The Friend Who Doesn't Disappear

Saras Growth Space — Sun, 04 Oct 2026 20:16:45 +0000

There is a particular kind of loneliness that is difficult to explain.

It's not being alone.

It's having someone you care about slowly disappear from your life — and realizing that if you stop initiating, checking in, reminding, planning, and asking, the relationship seems to stop moving altogether.

You send the message.

You ask how they're doing.

You remember the important dates.

You make the plans.

You remind them to call.

And eventually, you start wondering:

“Why do I always have to remind you that I exist?”

So for this challenge, I want to build something for a friend.

Not another chatbot.

Not another productivity app.

I want to build a small AI-powered device whose job is much simpler:

Help you show up for the people you care about.

Meet the device

Imagine a small device sitting on your desk.

It has a microphone, a small display, a speaker, and a physical button.

You talk to it naturally.

You might say:

“Alex has been having a really difficult week. I should check in on him tomorrow.”

The device doesn't just turn that into a calendar reminder.

It stores the context.

Later, it might tell you:

“Hey. You mentioned Alex was having a rough week. You haven't checked in yet. Want to call him?”

That's the difference I want to explore.

A normal reminder remembers what you asked it to remember.

An AI-powered companion can potentially remember why it mattered.

Under the hood

The interesting part isn't putting an LLM inside a box.

The interesting part is giving the model the right kind of memory and letting it reason over time.

I'd design the system roughly like this:

              ┌────────────────────┐
              │      YOU           │
              │ voice / button /   │
              │ simple interaction │
              └─────────┬──────────┘
                        │
                        ▼
              ┌────────────────────┐
              │ Speech-to-Text     │
              │      (local)       │
              └─────────┬──────────┘
                        │
                        ▼
              ┌────────────────────┐
              │   Open LLM         │
              │ intent + context   │
              │ extraction         │
              └─────────┬──────────┘
                        │
              ┌─────────┴─────────┐
              ▼                   ▼
       ┌──────────────┐    ┌───────────────┐
       │ Relationship │    │   Temporal    │
       │    Memory    │    │    Engine     │
       └──────┬───────┘    └───────┬───────┘
              │                    │
              └─────────┬──────────┘
                        ▼
              ┌────────────────────┐
              │  Context / RAG     │
              │  Retrieve relevant │
              │  memories          │
              └─────────┬──────────┘
                        │
                        ▼
              ┌────────────────────┐
              │   Check-in Engine  │
              │ Should I intervene?│
              └─────────┬──────────┘
                        │
                        ▼
              ┌────────────────────┐
              │  Device Response   │
              │ screen / voice /   │
              │ gentle notification │
              └────────────────────┘

The important component here is not the LLM alone.

It's the combination of:

LLM + memory + time + context + a decision layer.

A memory for relationships

I'd give the system a small local memory store.

Not a giant database containing everything you've ever said.

Only information that is useful for helping you show up.

For example:

{
  "person": "Alex",
  "relationship": "friend",
  "context": [
    "having a difficult week at work",
    "interview on Friday"
  ],
  "commitments": [
    "check in this week",
    "help with interview preparation"
  ],
  "last_interaction": "2026-10-01"
}

The LLM can convert natural language into structured memories.

So:

“Alex has an interview Friday. I told him I'd help him prepare.”

could become:

Person: Alex

Event:
  Interview
  Date: Friday

Commitment:
  Help Alex prepare

Suggested follow-up:
  Before Friday

This makes the system much more reliable than simply throwing an entire conversation history into a model every time.

The temporal layer

This is where I think the idea gets particularly interesting.

The system shouldn't constantly interrupt you.

If it did, we'd just create another annoying notification machine.

Instead, there should be a check-in engine.

It could consider signals such as:

How long since you last contacted someone
Whether you previously said you'd follow up
Whether an important event is approaching
Whether you've repeatedly postponed something
Whether the person was going through something difficult
Whether you've already been reminded recently
Whether this is actually important enough to interrupt you

The AI then decides:

NO ACTION
       │
       ├── not important
       ├── too soon
       └── already handled

GENTLE NUDGE
       │
       └── "Maybe check in with Alex."

IMPORTANT
       │
       └── "You said you'd help Alex today."

URGENT
       │
       └── only for situations explicitly configured

The goal isn't maximum notifications.

It's minimum intervention for maximum human connection.

Retrieval-Augmented Friendship

This is also where a lightweight RAG architecture could help.

Instead of giving the LLM every memory, the system retrieves only memories relevant to the current situation.

For example:

“Should I remind this person about Alex?”

The retrieval layer could find:

Alex
↓
Last conversation
↓
Work problem
↓
Upcoming interview
↓
Promise to help
↓
Last contact: 6 days ago

The model then gets that context and generates:

“You said you'd help Alex prepare for his interview. It's tomorrow and you haven't checked in. Want to send him a message?”

That feels much more like context-aware assistance than a conventional reminder.

Voice-first interaction

I also don't want this to be another app where you have to open a screen, navigate five menus and type something.

The interaction should be almost conversational.

You:

“I should probably call Maya sometime this week.”

Device:

“Want me to keep an eye on that?”

You:

“Yeah.”

Three days later:

Device:

“You haven't called Maya yet. It's Wednesday. Want to do it now?”

You:

“Not right now.”

Device:

“Okay. I'll leave it alone.”

That last part is important.

The AI needs to understand when to shut up.

Open-source AI is important here

This is a particularly personal application of AI.

The system potentially knows:

who your closest friends are
who you're worried about
what people are going through
promises you've made
personal conversations
relationship patterns

I don't think all of that should automatically become cloud data.

That's why I'd want the intelligence layer to use open-weight models that can run locally or on hardware you control, wherever practical.

A possible stack could look like:

Hardware
├── Raspberry Pi / similar SBC
├── Microphone
├── Speaker
└── Small display

AI
├── Local speech-to-text
├── Open-weight LLM
├── Embedding model
└── Lightweight local database

Application
├── Memory extraction
├── Vector retrieval
├── Temporal reasoning
├── Check-in policy
└── Voice/UI layer

The exact model isn't the point yet.

The architectural principle is:

Your relationships should belong to you.

And there needs to be a boundary

I don't want this thing pretending to be your friend.

It shouldn't message people pretending to be you.

It shouldn't manufacture emotional conversations.

It shouldn't decide:

“You don't talk to Sarah enough, so I'll message her.”

Absolutely not.

The human remains responsible for the relationship.

The AI simply notices things we are often terrible at noticing.

It says:

“You said you'd be there.”

And then leaves the choice to you.

The feature I care about most

There's one feature I'd really want to experiment with.

A relationship health view.

Not a score like:

Friendship: 72%

That would be creepy and meaningless.

Instead, something like:

PEOPLE YOU SAID YOU'D CHECK IN ON

Alex       6 days
Maya       3 days
Daniel     11 days ⚠️

PROMISES YOU HAVEN'T FOLLOWED UP ON

✓ Send Maya the document
⚠ Help Alex prepare for interview
⚠ Call Daniel

UPCOMING

Tomorrow — Alex's interview
Friday — Maya's birthday

It's essentially a memory prosthetic for being a better friend.

But this isn't really about productivity

That's the part I keep coming back to.

We've built endless technology to help us:

work faster
answer emails
manage calendars
optimize sleep
track money
complete tasks

But relationships are messy.

People forget.

People get busy.

People don't always know how to ask for help.

And sometimes someone disappears from your life simply because nobody remembered to reach out.

I don't want to build an AI that makes people more productive.

I want to build something that helps people become more present.

Because sometimes the most important thing on your to-do list isn't:

Finish the report.

It's:

Call your friend.

Sometimes it's:

Ask how they're actually doing.

Sometimes it's:

Show up.

And sometimes your friend shouldn't have to disappear completely before you realize they needed you.

So that's what I'd like to build:

A small, open-source AI device that remembers the people you said you'd be there for.

Not an AI friend.

Not a replacement for human connection.

Just a little machine that can look at you and say:

“Dude. I need you to help me here.”

“Be there.”

“Don't make them remind you every day that they exist.”

LLD Design Patterns: How We'll Learn Design Patterns Throughout This Series

Saras Growth Space — Sat, 08 Aug 2026 03:30:00 +0000

So far in this mini-series, we've answered the biggest questions that confuse developers when they first encounter Design Patterns.

We've learned:

why SOLID isn't the final destination,
why recurring design problems exist,
why copying code doesn't create good design,
what Design Patterns really are,
how experienced engineers recognize them,
and how every pattern can be understood through its Problem, Intent, Solution, and Consequences.

Now it's time to answer one final question before we begin exploring the individual patterns.

How should we learn Design Patterns so that we can actually use them in real-world software instead of just recognizing their names?

The answer may surprise you.

We're not going to learn Design Patterns the way they're usually taught.

The Traditional Way of Learning Design Patterns

Open almost any Design Patterns book or tutorial, and you'll often see something like this.

Pattern Name

↓

Definition

↓

UML Diagram

↓

Code Example

↓

Advantages

↓

Disadvantages

Technically, there's nothing wrong with this approach.

But many developers finish reading the chapter and still wonder:

"When would I ever use this?"

That's because they learned the solution before understanding the problem.

It's like learning how to use a fire extinguisher before understanding what kinds of fires it can safely put out.

Knowledge without context is difficult to apply.

The Way Experienced Engineers Learn

Experienced engineers don't begin with the pattern.

They begin with the software.

They observe where the current design starts struggling.

Only then do they search for a better design approach.

Their thinking looks more like this.

Business Requirement

↓

Design Challenge

↓

Current Design Starts Breaking

↓

Understand Why

↓

Explore Better Design

↓

Recognize a Design Pattern

The pattern is never the starting point.

It's the result of understanding the problem.

The Learning Framework We'll Use

Every pattern in this series will follow exactly the same structure.

Business Problem
        ↓
Design Problem
        ↓
Naive Solution
        ↓
Why It Breaks
        ↓
Pattern Intuition
        ↓
Pattern Structure
        ↓
Real-World Example
        ↓
LLD Thinking
        ↓
Trade-offs
        ↓
Interview Perspective

By following the same framework every time, you'll stop memorizing isolated patterns and start recognizing recurring design problems.

Let's understand why each step matters.

Step 1. Start with the Business Problem

Every software system exists to solve a business problem.

For example:

Customers can choose multiple payment methods.
Users receive notifications through different channels.
Pricing rules vary by customer type.
External systems must be integrated.

At this stage, we don't think about classes or patterns.

We simply understand what the business needs.

Step 2. Identify the Design Problem

Business requirements eventually create design challenges.

For example:

Object creation becomes difficult.
Behavior changes frequently.
Components become tightly coupled.
Integrations become messy.

This is where software engineering begins.

Different business requirements can lead to the same design problem.

That's why Design Patterns are reusable across industries.

Step 3. Build the Naive Solution

Before introducing any Design Pattern, we'll first build the obvious solution.

Usually, it works.

At least initially.

This is important because every Design Pattern exists to solve a weakness in a simpler design.

If we skip the naive solution, the pattern feels unnecessary.

If we experience its limitations first, the pattern feels inevitable.

Step 4. Understand Why the Design Starts Breaking

As systems evolve, the naive design starts showing symptoms.

Perhaps:

every new feature requires editing existing code,
object creation becomes duplicated,
classes know too much,
communication becomes tangled,
testing becomes difficult.

Instead of immediately replacing the design, we'll first understand why it struggles.

This builds engineering intuition rather than pattern memorization.

Step 5. Introduce the Pattern Naturally

Only now will we introduce the Design Pattern.

Not as a clever trick.

Not as a predefined template.

But as a natural response to the problem we've already experienced.

By this point, the pattern should feel obvious.

Readers should think:

"Of course this design is better."

That's exactly how experienced engineers discover patterns in real projects.

Step 6. Apply the Pattern to a Real System

Every pattern will be demonstrated using realistic domains such as:

Amazon
BookMyShow
Ride Sharing
Food Delivery
Banking
Hospital Management
Inventory Systems

The goal isn't simply to understand the pattern.

It's to recognize where it appears in real software.

Step 7. Discuss the Trade-offs

One of the biggest misconceptions about Design Patterns is that they are always the "best" solution.

They're not.

Every pattern introduces trade-offs.

Sometimes the added flexibility is worth the additional complexity.

Sometimes it isn't.

We'll discuss both sides honestly.

Learning when not to use a pattern is just as valuable as learning when to use one.

Step 8. Finish with Interview Thinking

Finally, we'll connect each pattern to interview scenarios.

Instead of memorizing definitions, you'll learn how to explain:

the problem,
the reasoning,
the trade-offs,
and the design decisions.

That's exactly what strong interview answers are built upon.

Weak Thinking vs Strong Thinking

Weak Thinking

"Today I'm learning the Factory Method Pattern."

Strong Thinking

"Today I'm learning why object creation becomes a design problem, and why experienced engineers eventually arrive at Factory Method."

The pattern is the destination.

The design problem is the journey.

Common Beginner Mistake

Many developers treat Design Patterns like a glossary.

They read one chapter.

Memorize the UML.

Move to the next pattern.

A few months later, everything feels disconnected.

Instead, we'll build one continuous story.

Every new pattern will solve a problem we've already experienced.

This makes the learning process much more intuitive—and much easier to remember.

Interview Perspective

Interviewers don't expect candidates to recall textbook definitions.

They want to understand how you think.

If you can explain:

the business problem,
the design challenge,
why the naive solution breaks,
and why a particular pattern improves the design,

you'll demonstrate a much deeper understanding than someone who simply names the pattern.

Key Insight

Design Patterns are not isolated topics to memorize.

They're solutions to recurring design problems.

That's why this series won't teach patterns as independent chapters.

We'll discover them the same way experienced engineers do—by solving real design challenges step by step.

In This Article, You Learned

Why we'll follow a problem-first approach throughout this series.
The learning framework that every upcoming pattern article will use.
Why naive solutions are an important part of understanding Design Patterns.
How this approach builds long-term engineering intuition instead of short-term memorization.

One-Line Takeaway

Don't learn Design Patterns as answers—learn them as solutions to design problems you've already understood.

LLD Design Patterns: A Simple Roadmap to the 23 GoF Design Patterns

Saras Growth Space — Sat, 08 Aug 2026 02:30:00 +0000

Over the last few articles, we've answered some fundamental questions.

Why do Design Patterns exist?
Why isn't SOLID enough?
Why don't good designs emerge from copying code?
What exactly is a Design Pattern?
Why do experienced engineers recognize problems instead of memorizing pattern names?

Now we're finally ready to answer another important question.

What are these famous "23 GoF Design Patterns" everyone talks about?

Many beginners imagine they are 23 unrelated techniques that must be memorized individually.

Fortunately, that's not true.

Once you understand why they are grouped together, learning them becomes much easier.

Before the Patterns, There Was a Problem

Imagine you're building software over many years.

Every project is different.

Different industries.

Different programming languages.

Different business rules.

Yet certain design problems keep appearing.

Sometimes the challenge is:

"How should this object be created?"

Sometimes it's:

"How should these objects work together?"

Other times it's:

"How can this behavior change without rewriting existing code?"

Experienced engineers noticed something interesting.

Although projects differed, these questions kept repeating.

Instead of treating every solution as completely unique, they began organizing similar solutions into groups.

That's exactly how the GoF Design Patterns are structured.

Why the Patterns Are Divided Into Three Families

The 23 patterns aren't organized alphabetically.

They're organized by the kind of design problem they solve.

Think of visiting a hospital.

Doctors don't organize diseases alphabetically.

They organize them into categories because similar problems often require similar thinking.

Software engineering follows the same principle.

Instead of asking:

"Which pattern should I memorize first?"

We ask:

"What kind of design problem am I facing?"

The answer usually points us toward one of three families.

1. Creational Patterns

Sometimes the hardest part of a design isn't using an object.

It's deciding how that object should be created.

Imagine an e-commerce application.

Should the checkout service directly create every payment gateway?

Should object creation be centralized?

Should different products be created differently depending on configuration?

These are object creation problems.

Creational Patterns help us answer questions such as:

Who creates an object?
When should it be created?
Which implementation should be instantiated?
How can creation remain flexible as requirements evolve?

We'll explore patterns like:

Singleton
Factory Method
Abstract Factory
Builder
Prototype

Don't worry about what each one does yet.

For now, simply remember:

Creational Patterns focus on object creation.

2. Structural Patterns

Now imagine all your objects already exist.

The next challenge appears.

How should they work together?

Suppose your application integrates with an external shipping provider.

Or maybe several existing classes need to appear as one simplified interface.

Perhaps unrelated systems must communicate without changing their internal implementations.

These are structural problems.

Structural Patterns focus on organizing relationships between objects.

They help us answer questions like:

How should existing objects collaborate?
How can incompatible systems work together?
How can functionality be added without rewriting existing classes?

Some well-known Structural Patterns include:

Adapter
Decorator
Facade
Proxy
Composite
Bridge

Again, don't memorize them.

Just recognize the category.

Structural Patterns focus on organizing objects.

3. Behavioral Patterns

Finally, imagine your objects already exist and are connected properly.

Now another question appears.

How should they behave?

Consider an online shopping application.

Different pricing strategies.

Different notification channels.

Different order states.

Different approval workflows.

Different ways for components to communicate.

These are behavioral problems.

Behavioral Patterns focus on how objects interact, collaborate, and make decisions.

They answer questions like:

How should behavior change?
How should multiple objects communicate?
How should requests flow through the system?
How should algorithms remain interchangeable?

Examples include:

Strategy
Observer
Command
State
Template Method
Iterator
Mediator
Chain of Responsibility
Visitor

Once again, don't worry about remembering every name.

Focus on the type of problem.

Behavioral Patterns focus on object behavior and collaboration.

A Simple Mental Model

Instead of remembering 23 independent patterns, remember three questions.

Am I struggling to create objects?
        ↓
Creational

Am I struggling to organize objects?
        ↓
Structural

Am I struggling to manage behavior between objects?
        ↓
Behavioral

This simple roadmap is far easier to remember than a long list of pattern names.

More importantly, it's how experienced engineers naturally think.

Weak Thinking vs Strong Thinking

Weak Thinking

"I need to memorize all 23 Design Patterns."

Strong Thinking

"First identify the type of design problem. Then explore the family of patterns designed to solve it."

The family comes before the individual pattern.

Common Beginner Mistake

Many developers print a chart of all 23 GoF patterns and try to memorize each definition.

A week later, they remember almost nothing.

Why?

Because isolated facts are difficult to retain.

Instead, build your understanding in layers.

Identify the design problem.
Recognize the pattern family.
Learn the individual patterns one at a time.
Practice recognizing them in real systems.

This approach is much more natural and much easier to remember.

Interview Perspective

Interviewers rarely ask candidates to list all 23 GoF patterns.

Instead, they present a design problem.

For example:

"Object creation depends on runtime configuration."
"Third-party APIs have incompatible interfaces."
"Business algorithms change frequently."

Strong candidates first identify the category of problem.

Only then do they discuss a specific pattern.

This shows that they understand why the pattern exists—not just what it's called.

Key Insight

The GoF catalog isn't a collection of random solutions.

It's a map of recurring software design problems.

Each family addresses a different aspect of object-oriented design:

Creating objects.
Organizing objects.
Managing object behavior.

Once you understand this roadmap, learning individual patterns becomes much more intuitive.

In This Article, You Learned

Why the 23 GoF Design Patterns are grouped into three families.
What kinds of problems each family addresses.
A simple mental model for recognizing which family to explore.
Why experienced engineers classify problems before choosing patterns.

One-Line Takeaway

Don't start by asking which Design Pattern to use—start by identifying whether your problem is about creating objects, organizing them, or managing their behavior.

LLD Design Patterns: How Experienced Engineers Recognize Patterns Instead of Memorizing Them

Saras Growth Space — Sat, 08 Aug 2026 01:30:00 +0000

By now, we've reached an important milestone in this series.

We've learned that:

SOLID principles help us design maintainable components.
Software keeps evolving even after we've applied good design principles.
The same categories of design problems appear across completely different projects.
Design Patterns are reusable design ideas—not reusable code.

At this point, many developers make a common mistake.

They open a Design Patterns book and start memorizing all 23 GoF patterns one by one.

Experienced engineers rarely learn them that way.

Instead, they develop something much more valuable:

The ability to recognize recurring design problems.

That's the real skill.

Imagine Walking Into a Hospital

Suppose you visit a doctor with a fever.

A beginner might focus only on the symptom.

"The patient has a fever."

An experienced doctor thinks differently.

They immediately ask:

What caused it?
Is it an infection?
Is it viral?
Is it bacterial?
Are there other symptoms?
What pattern do these symptoms resemble?

The diagnosis comes before the treatment.

Software design works exactly the same way.

Experienced engineers don't begin with a pattern.

They begin with the problem.

Beginners Search for Pattern Names

Imagine you're designing a payment system.

A beginner often thinks like this:

I know Singleton.

Can I use Singleton here?

Maybe Factory?

Or Strategy?

Which one should I choose?

The design starts with pattern names.

That's backwards.

The pattern becomes the goal instead of the solution.

Experienced Engineers Start With the Problem

Now consider how an experienced engineer approaches the same situation.

They ask questions like:

What is becoming difficult?
What keeps changing?
Where is the code tightly coupled?
What is likely to evolve?
Which responsibility is causing pain?
What is the business asking us to do repeatedly?

Only after understanding the problem do they consider whether a known design pattern fits.

Notice the difference.

The conversation is about the design challenge, not about GoF terminology.

Patterns Become Obvious When Problems Become Familiar

Suppose you're building an online shopping application.

The business says:

"Customers should be able to choose between multiple payment providers."

A beginner hears:

"Maybe I should use Factory."

An experienced engineer hears:

"The application shouldn't know which concrete payment implementation to create."

They're thinking about the underlying problem:

Object creation should be flexible.

The appropriate pattern naturally follows.

Another example.

The business says:

"Users can receive notifications through Email, SMS, Push, or WhatsApp."

A beginner asks:

"Which pattern handles notifications?"

An experienced engineer asks:

"How can different notification behaviors be added without changing existing business logic?"

Again, the problem is identified first.

Every Pattern Solves a Particular Kind of Problem

Think about the patterns you've probably heard of.

Even if you don't know their implementations yet, each exists because engineers repeatedly encountered a particular design challenge.

For example:

Need flexible object creation?
        ↓
Creational thinking

Need better collaboration between objects?
        ↓
Structural thinking

Need flexible behavior?
        ↓
Behavioral thinking

The names are less important than the questions they answer.

That's why experienced engineers often recognize the right direction long before they think of a specific pattern.

They Build a Mental Library of Problems

Imagine an experienced architect designing buildings.

They don't memorize thousands of blueprints.

Instead, they recognize situations.

"This building needs better ventilation."

"This one needs earthquake resistance."

"This requires emergency exits."

Over time, they build a mental library of recurring engineering problems.

Software engineers do the same thing.

Eventually, they notice patterns like:

"I've seen this object creation problem before."
"I've seen this communication problem before."
"I've seen this extension problem before."

That recognition is far more valuable than remembering definitions.

Pattern Names Are Just Vocabulary

Consider the word Strategy.

The name itself doesn't solve anything.

It's simply a convenient label.

When two experienced engineers discuss a design, they might say:

"This looks like a Strategy."

What they're really communicating is much richer.

They're saying:

the behavior varies,
the algorithms should remain independent,
new behaviors should be easy to add,
the rest of the system shouldn't know the implementation details.

The pattern name is just shorthand for an entire design idea.

That's why understanding always comes before memorization.

Weak Thinking vs Strong Thinking

Weak Thinking

"Which Design Pattern should I use here?"

Strong Thinking

"What recurring design problem am I trying to solve?"

Once the problem is clear, the appropriate pattern often becomes much easier to identify.

Common Beginner Mistake

Many developers try to memorize Design Patterns like interview questions.

They make flashcards.

They remember UML diagrams.

They memorize definitions.

Then, during an interview, they struggle to apply them because they don't recognize the underlying design problem.

Experienced engineers work in the opposite direction.

They first understand the design challenge.

Only then do they name the pattern.

That's why they rarely need to memorize pattern definitions.

They remember the problems instead.

Interview Perspective

Suppose an interviewer says:

"Our pricing algorithm changes frequently."

A weak response might be:

"We should use the Strategy Pattern."

A stronger response sounds like this:

"Since pricing algorithms are expected to change independently of the rest of the application, I'd like to separate each pricing behavior into its own implementation so new algorithms can be introduced without modifying existing business logic."

Only after explaining that reasoning would you mention Strategy.

Interviewers value your thinking far more than your terminology.

Key Insight

Experienced engineers don't carry a list of 23 Design Patterns in their heads.

They carry a mental library of recurring design problems.

When a familiar problem appears, the appropriate pattern naturally comes to mind.

The problem leads.

The pattern follows.

In This Article, You Learned

Why experienced engineers focus on problems instead of pattern names.
How recurring design challenges become easier to recognize over time.
Why Design Pattern names are simply shared engineering vocabulary.
Why understanding problems is more valuable than memorizing definitions.

One-Line Takeaway

Don't memorize Design Patterns—learn to recognize the recurring design problems that make them useful.

LLD Design Patterns: The Four Things Every Design Pattern Contains

Saras Growth Space — Sat, 08 Aug 2026 00:30:00 +0000

In the previous articles, we answered some fundamental questions.

We learned:

why Design Patterns exist,
why they are not reusable code,
and why experienced engineers recognize patterns instead of memorizing them.

Now we're ready for an important shift.

From this point onward, we'll start learning individual Design Patterns.

Before we do that, there's one skill that will make every future pattern much easier to understand.

Every Design Pattern can be understood by answering the same four questions.

Once you learn these four questions, you won't have to memorize patterns individually.

Instead, you'll know exactly how to read any pattern description, whether it's from a book, documentation, or an interview question.

Why Beginners Find Design Patterns Overwhelming

Imagine opening a Design Patterns book for the first time.

You see terms like:

Singleton
Factory Method
Adapter
Strategy
Observer
Proxy
Visitor

Every chapter looks different.

Every UML diagram looks different.

Every example uses different classes.

It feels like you're learning 23 unrelated concepts.

That's because most beginners focus on the implementation.

Experienced engineers focus on something much simpler.

They ask the same four questions every single time.

The Four Questions Behind Every Design Pattern

Whenever you encounter a new Design Pattern, ask yourself:

1. What problem exists?

↓

2. What is the pattern trying to achieve?

↓

3. How does it solve that problem?

↓

4. What trade-offs come with this solution?

Those four questions correspond to four fundamental parts of every Design Pattern:

Problem
Intent
Solution
Consequences

Let's understand each one.

1. Problem — Why Does This Pattern Exist?

Every Design Pattern starts with a problem.

Not a business problem.

A design problem.

For example:

Object creation has become complicated.
Different algorithms keep changing.
Components are tightly coupled.
External systems have incompatible interfaces.
New features require modifying existing classes.

Notice something important.

The pattern didn't appear because someone wanted to invent a clever design.

It appeared because software teams repeatedly faced the same engineering challenge.

Whenever you study a new pattern, your first question should always be:

What recurring design problem made this pattern necessary?

If you skip this step, the pattern becomes something to memorize instead of something to understand.

2. Intent — What Is the Pattern Trying to Achieve?

Once the problem is clear, the next question is:

What is the overall goal?

This is called the Intent of the pattern.

Think of it as the one-sentence purpose.

For example:

simplify object creation,
separate changing behavior,
allow incompatible systems to work together,
reduce coupling,
add functionality dynamically.

The intent doesn't explain implementation.

It simply tells you what the pattern is trying to accomplish.

A useful way to think about it is:

Problem

↓

Intent

"I want to solve this problem by achieving this goal."

3. Solution — How Does the Pattern Solve the Problem?

Only now do we ask:

How does the pattern actually solve the problem?

This is the part many beginners jump to first.

They immediately start studying UML diagrams and code.

Experienced engineers do the opposite.

Once they understand the problem and intent, the solution becomes much easier to appreciate.

The solution usually describes:

the participating objects,
their responsibilities,
how they collaborate,
and how the design is organized.

Notice that the solution is not a code template.

Different programming languages will implement the same pattern differently.

The important part is the underlying design idea.

4. Consequences — What Do We Gain and What Do We Sacrifice?

Every engineering decision involves trade-offs.

Design Patterns are no exception.

A pattern usually solves one problem while introducing another consideration.

For example:

additional classes,
increased abstraction,
slightly higher complexity,
extra indirection,
improved flexibility.

Experienced engineers never ask:

"Is this pattern good?"

Instead, they ask:

"Is this trade-off worthwhile for my system?"

That's why the Consequences section is just as important as the Solution section.

Ignoring trade-offs is one of the biggest reasons beginners misuse Design Patterns.

Reading Any Pattern Becomes Much Easier

Suppose tomorrow you encounter a pattern you've never seen before.

Instead of feeling overwhelmed, use this simple checklist.

What problem is recurring?

↓

What is the pattern trying to achieve?

↓

How is the solution organized?

↓

What are the trade-offs?

You'll be surprised how quickly unfamiliar patterns start making sense.

This approach works whether you're reading:

the GoF book,
a technical blog,
framework documentation,
or preparing for interviews.

Weak Thinking vs Strong Thinking

Weak Thinking

"Let me memorize this UML diagram."

Strong Thinking

"Why was this pattern invented? What problem was it trying to solve?"

Once you answer that question, the rest of the pattern becomes much easier to understand.

Common Beginner Mistake

Many developers spend hours memorizing:

class names,
object relationships,
code implementations,
UML diagrams.

Then they forget everything a few weeks later.

Why?

Because they memorized the solution without understanding the problem.

Experienced engineers rarely have this issue.

They remember the problem first.

The solution naturally follows.

Interview Perspective

Suppose an interviewer asks:

"Can you explain the Strategy Pattern?"

A weak answer sounds like:

"It has a Context class and several Strategy implementations."

A stronger answer starts differently:

"It's useful when an application has multiple interchangeable algorithms, and we want to switch between them without changing the code that uses them."

Notice the order.

Problem
Intent
Solution
Trade-offs

That's how interviewers expect experienced engineers to explain patterns.

Key Insight

Although the 23 GoF Design Patterns solve different problems, they all share the same structure.

Every pattern exists because:

a recurring design problem appeared,
engineers had a clear objective,
they discovered a proven solution,
and they accepted certain trade-offs.

Once you understand this framework, every future pattern becomes much easier to learn.

In This Article, You Learned

The four building blocks shared by every Design Pattern.
Why understanding the problem is more important than memorizing the implementation.
How to read any Design Pattern systematically.
Why trade-offs are an essential part of every design decision.

One-Line Takeaway

Don't start a Design Pattern by reading its code—start by understanding its problem, intent, solution, and consequences.

LLD Design Patterns: What Design Patterns Really Are

Saras Growth Space — Fri, 07 Aug 2026 23:30:00 +0000

By now, we've built a strong foundation.

We've learned that:

SOLID principles help us design better classes.
Real-world software keeps evolving.
The same design problems appear across different projects.
Simply copying code from another project doesn't solve those problems.

This naturally leads to one important question.

If Design Patterns aren't reusable code, then what exactly are they?

Many developers hear terms like Singleton, Factory, or Observer and imagine they are libraries, frameworks, or predefined templates.

They're none of these.

Understanding what a Design Pattern truly is is far more important than memorizing all 23 GoF patterns.

Every Profession Develops Proven Solutions

Imagine you're learning to drive.

Over time, experienced drivers recognize familiar situations.

Approaching a sharp turn.
Driving in heavy rain.
Overtaking another vehicle.
Parking in a tight space.

Each situation has a proven way of handling it.

Experienced drivers don't invent a new technique every time.

They recognize the situation and apply an approach that has worked repeatedly.

Software engineering works exactly the same way.

As engineers built increasingly complex systems over decades, they noticed something interesting.

Different applications kept encountering the same kinds of design problems.

Eventually, proven solutions began to emerge.

Those recurring solutions became known as Design Patterns.

A Design Pattern Is a Proven Solution to a Recurring Design Problem

Notice the wording carefully.

A Design Pattern is not a solution to a specific business problem.

For example:

Business problem:

Customers should receive notifications through Email and SMS.

That's not a Design Pattern.

Instead, engineers ask a different question.

How can multiple parts of the system react when something important happens?

Now we're looking at a recurring design problem.

Many systems need to notify interested components when an event occurs.

The business context changes.

The design challenge stays remarkably similar.

That's where a Design Pattern becomes useful.

A Design Pattern is a proven way of organizing software to solve a recurring design problem.

The emphasis is on organizing software, not writing identical code.

Patterns Capture Experience

Imagine thousands of software teams across the world.

Different countries.

Different programming languages.

Different industries.

Different technologies.

Yet many teams independently discover similar approaches for solving the same design challenge.

Over time, those successful approaches become shared engineering knowledge.

A Design Pattern is essentially that shared experience.

Instead of learning every lesson through trial and error, you benefit from decades of software engineering experience.

Patterns don't eliminate thinking.

They accelerate it.

A Pattern Describes How to Think, Not What to Type

Suppose you're building an application that supports multiple payment methods.

One project might use Java.

Another uses Python.

Another uses Go.

Another uses C#.

The code will obviously look different.

But the underlying idea can remain the same.

The pattern guides your thinking.

It doesn't dictate your syntax.

This is why Design Patterns have survived for decades despite the constant evolution of programming languages and frameworks.

Technologies change.

Good design ideas remain valuable.

Think of a Recipe Instead of a Meal

Imagine someone gives you a recipe for baking bread.

The recipe isn't the bread itself.

It explains:

what ingredients are involved,
how they work together,
the order of preparation,
and why each step matters.

Two people following the same recipe may still produce different results.

The flour may differ.

The oven may differ.

The baking time may vary.

The recipe provides structure—not identical outcomes.

A Design Pattern plays a similar role.

It provides a proven design approach.

Your implementation will still depend on your application's requirements, constraints, and technology choices.

Design Patterns Are About Relationships

One common misconception is that Design Patterns are about individual classes.

They're not.

Most patterns describe how multiple objects collaborate.

For example:

Who creates an object?
Who owns it?
Who communicates with whom?
How can behavior change without modifying existing code?
How can unrelated components remain loosely coupled?

These are questions about relationships.

That's why Design Patterns naturally build on top of Object-Oriented Design and SOLID.

Once you know how to design good classes, the next challenge is organizing how those classes work together.

Weak Thinking vs Strong Thinking

Weak Thinking

"A Design Pattern is a piece of reusable code."

Strong Thinking

"A Design Pattern is a reusable design idea that helps solve recurring software design problems."

That single mindset shift changes how you approach software engineering.

Common Beginner Mistake

Many beginners ask:

"Which Design Pattern should I memorize first?"

Experienced engineers ask a different question:

"What kind of design problem am I trying to solve?"

The pattern comes after understanding the problem.

Not before.

If you start with the pattern name, you'll often force it into situations where it doesn't belong.

If you start with the problem, the appropriate pattern becomes much easier to recognize.

Interview Perspective

Interviewers aren't impressed by candidates who can list all 23 GoF patterns.

They're impressed by candidates who can explain why a particular design approach makes sense.

For example:

Instead of saying,

"I'll use the Observer Pattern."

A stronger explanation is:

"Multiple independent components need to react whenever an order is placed, but I don't want the order service to depend directly on all of them."

You've described the design problem.

The pattern becomes the logical solution.

That's the kind of reasoning interviewers look for.

Key Insight

Design Patterns are not libraries.

They are not frameworks.

They are not reusable code templates.

They are proven design ideas that capture decades of software engineering experience and help us solve recurring design problems in a structured way.

In This Article, You Learned

What a Design Pattern actually is.
Why patterns solve design problems rather than business problems.
Why patterns describe relationships instead of code.
Why experienced engineers treat patterns as reusable thinking, not reusable implementations.

One-Line Takeaway

A Design Pattern is not reusable code—it's reusable engineering experience applied to recurring design problems.

LLD Design Patterns: Why Copying Good Code Doesn't Produce Good Design

Saras Growth Space — Fri, 07 Aug 2026 22:30:00 +0000

In the previous article, we discovered something interesting.

Whether you're building an e-commerce platform, a banking application, a ride-sharing service, or a hospital management system, the same categories of design problems keep appearing.

That's why experienced software engineers don't reinvent every solution from scratch.

So a natural question arises:

If these problems keep repeating, why don't we simply copy the solution from another project?

At first, that sounds reasonable.

After all, if a payment module worked well in one application, why not reuse the same code everywhere?

The answer reveals one of the biggest misconceptions beginners have about Design Patterns.

Software Is Reused Less Than Problems Are

Imagine two companies.

The first builds an online food delivery platform.

The second builds an airline reservation system.

Their businesses are completely different.

One manages restaurants.

The other manages flights.

One deals with delivery partners.

The other deals with aircraft and passengers.

At first glance, these systems seem unrelated.

But as development progresses, both teams encounter surprisingly similar questions.

How should objects be created?
How should different algorithms be selected?
How should external systems be integrated?
How should independent components communicate?
How can new features be added without rewriting existing code?

The problems look almost identical.

The code does not.

Code Depends on Context

Consider a payment service inside an online shopping platform.

It might look something like this.

PaymentService
    ├── StripeGateway
    ├── OrderRepository
    ├── CustomerService
    └── InvoiceGenerator

Now imagine copying this implementation into a hospital management system.

Immediately, several dependencies stop making sense.

There is no OrderRepository.

Invoices work differently.

The payment workflow is different.

Business rules are different.

The code that looked reusable suddenly becomes tightly coupled to its original project.

The implementation cannot simply be copied.

Business Rules Always Change

Imagine two ride-sharing companies.

Both calculate ride fares.

Company A considers:

distance
time
demand

Company B considers:

distance
driver rating
city-specific regulations
subscription discounts

Both companies solve the same kind of problem:

Calculate the ride price.

But their business rules are completely different.

Even if you copied the pricing code from one company, you'd spend more time modifying it than understanding the underlying design.

The problem is reusable.

The implementation is not.

Good Design Is About Adaptation

Think about architecture in the real world.

An architect designing a hospital doesn't copy the blueprint of a shopping mall.

The buildings serve different purposes.

The rooms are different.

The regulations are different.

The layouts are different.

Yet architects still reuse ideas.

Emergency exits.

Elevators.

Fire safety.

Ventilation.

Structural engineering principles.

They reuse proven solutions—not identical buildings.

Software engineering works the same way.

Experienced engineers reuse ideas, not entire systems.

The Real Asset Isn't the Code

When beginners discover Design Patterns, they often expect something like this.

Need notifications?

↓

Copy these 200 lines of code.

↓

Problem solved.

That's not how Design Patterns work.

A Design Pattern doesn't say:

"Write this exact code."

Instead, it says:

"When you encounter this type of recurring problem, experienced engineers usually organize their design in this way."

That's a completely different mindset.

Why Blind Copying Often Makes Software Worse

Imagine copying a complex notification framework from a large enterprise application into a simple startup project.

The original system supported:

Email
SMS
Push notifications
WhatsApp
Slack
Webhooks
Retry queues
Audit logs

Your application only sends one email.

Instead of simplifying development, you've introduced unnecessary complexity.

This violates one of the design principles we've already discussed in this series:

YAGNI — You Aren't Gonna Need It.

Good design isn't about copying the most sophisticated solution.

It's about solving today's problem with a design that can evolve tomorrow.

Weak Thinking vs Strong Thinking

Weak Thinking

"That project used this code, so I'll copy it."

Strong Thinking

"That project solved a similar design problem. Let me understand why that solution worked before applying the same idea."

Experienced engineers reuse reasoning.

Not repositories.

Common Beginner Mistake

Many developers search for Design Patterns the same way they search for algorithms.

They expect:

Problem

↓

Pattern

↓

Finished code

But software design doesn't work like that.

Every project has:

different requirements,
different constraints,
different business rules,
different performance goals,
different teams,
different technologies.

The code will naturally be different.

What remains consistent is the underlying design idea.

Interview Perspective

One of the fastest ways to signal inexperience during an interview is to say:

"I'd use the Strategy Pattern because that's what I used in my last project."

A stronger answer sounds like this:

"The behavior changes frequently and new algorithms will continue to be added. I want to separate those algorithms from the rest of the system so that new ones can be introduced without modifying existing business logic."

Notice the difference.

The second answer explains the problem first.

The pattern becomes the natural consequence of good design thinking.

That's exactly how experienced interviewers expect candidates to reason.

Key Insight

Projects rarely share identical code.

But they often share identical design challenges.

Design Patterns were never created so engineers could copy implementations.

They were created so engineers could recognize recurring problems and apply proven design ideas in their own context.

In This Article, You Learned

Why reusable code and reusable design are different concepts.
Why implementations depend heavily on business context.
Why experienced engineers reuse ideas instead of copying projects.
Why understanding a design problem matters more than copying its solution.

One-Line Takeaway

Good engineers don't copy code—they understand the design idea that made the code successful.

LLD Design Patterns: The Problems SOLID Was Never Designed to Solve

Saras Growth Space — Fri, 07 Aug 2026 21:30:00 +0000

In the previous article, we answered an important question:

What does SOLID actually solve?

We saw that SOLID helps us design software that is easier to understand, maintain, test, and extend by improving the quality of individual classes and their relationships.

But software engineering doesn't stop there.

Even when every class follows SOLID principles, experienced engineers continue to encounter a different category of problems.

These problems don't indicate that SOLID has failed.

They simply belong to a different level of design.

Understanding this distinction is one of the biggest mindset shifts in becoming a better software engineer.

Good Design Doesn't Mean Every Problem Disappears

Imagine you've built an e-commerce application.

You've carefully applied SOLID.

Every class has a single responsibility.
Dependencies are injected through interfaces.
Interfaces are small and focused.
The code is easy to test.

Everything looks clean.

Then the product team starts introducing new features.

Customers can pay using different payment providers.
Notifications can be sent through Email, SMS, Push, or WhatsApp.
Shipping partners vary by country.
Premium customers receive different pricing.
Recommendations use different algorithms.

Your classes are still well designed.

But new questions begin to appear.

Notice that these questions aren't about making a class smaller or splitting responsibilities.

They're about how multiple well-designed classes should work together.

SOLID Doesn't Decide How Objects Should Be Created

Suppose your application supports several payment gateways.

Stripe
PayPal
Razorpay
Apple Pay

A business rule says:

"Choose the appropriate payment provider based on the customer's selection."

Where should that decision live?

Should every service contain a long if-else statement?

Should each class create payment objects itself?

Should object creation be centralized?

These are important design questions.

SOLID doesn't prescribe the answer.

That's because object creation is a different design concern.

SOLID Doesn't Decide How Behavior Should Change

Imagine a ride-sharing application.

Pricing depends on many factors:

Standard ride
Premium ride
Airport ride
Peak hours
Festival pricing

Initially, the pricing logic is simple.

As new pricing rules arrive, the calculation becomes increasingly complex.

Now ask yourself:

How should the system switch between different pricing algorithms without constantly modifying existing code?

SOLID encourages extensibility.

But it doesn't define the mechanism for organizing interchangeable behaviors.

SOLID Doesn't Decide How Independent Components Communicate

Think about an online shopping platform.

When an order is placed, many things happen.

Order Created
      │
      ├── Inventory Updated
      ├── Payment Confirmed
      ├── Loyalty Points Added
      ├── Notification Sent
      └── Analytics Recorded

Should the OrderService directly call every other service?

If another feature is introduced tomorrow, should it be modified again?

Soon one service starts knowing too much about the rest of the system.

The issue isn't responsibility anymore.

The issue is communication.

SOLID doesn't define a general strategy for organizing interactions between many collaborating objects.

SOLID Doesn't Solve Integration Problems

Suppose your company integrates with a shipping partner.

Your system expects:

calculateShippingCost()

The shipping partner provides:

getFreightEstimate()

Both systems are correct.

Both work perfectly.

The challenge is simply that they speak different "languages."

No SOLID principle explains how to bridge incompatible interfaces.

That requires a different kind of design thinking.

SOLID Doesn't Tell You How to Add Features Dynamically

Imagine a coffee ordering application.

Customers can customize drinks.

Coffee

Later they add:

Coffee
 + Milk

Then:

Coffee
 + Milk
 + Caramel

Then:

Coffee
 + Milk
 + Caramel
 + Whipped Cream

Should you create a new class for every possible combination?

What happens when the menu grows?

The challenge is no longer about responsibility.

It's about extending behavior in a flexible way.

A Pattern Begins to Emerge

Look back at all the previous examples.

Although they belong to different domains, they're asking surprisingly similar questions.

Who should create objects?
How should behavior change dynamically?
How should components communicate?
How should incompatible systems work together?
How should features be added without creating an explosion of subclasses?

These questions appear in:

banking systems
e-commerce platforms
ride-sharing applications
hospital management systems
inventory systems
content platforms

The business domains are different.

The design problems are remarkably similar.

That observation changed the way experienced software engineers approached design.

Weak Thinking vs Strong Thinking

Weak Thinking

"Every new project has completely unique design challenges."

Strong Thinking

"Business requirements differ, but many underlying design problems repeat across projects."

Once you start recognizing recurring problems instead of isolated situations, you're thinking much more like an experienced engineer.

Common Beginner Mistake

Many developers believe that when their design starts becoming difficult, they simply haven't applied SOLID well enough.

Sometimes that's true.

But often, the responsibilities are already clear.

The real challenge lies elsewhere:

coordinating objects,
creating them,
extending them,
or allowing them to collaborate cleanly.

Trying to solve every problem with SOLID alone is like trying to fix every construction problem with better bricks.

Sometimes the challenge isn't the bricks.

It's the blueprint.

Interview Perspective

Interviewers often present scenarios that sound like business problems but are actually testing whether you recognize recurring design challenges.

For example:

"We need to support multiple payment gateways."
"Users can choose different notification channels."
"The pricing algorithm changes frequently."
"We're integrating with a third-party API."

They're not looking for pattern names immediately.

They're looking for whether you recognize the type of problem before proposing a solution.

Strong candidates identify the recurring design concern first.

Only then do they choose an appropriate pattern.

Key Insight

SOLID gives us principles for designing maintainable components.

As software grows, recurring challenges appear around object creation, behavior, communication, integration, and extension.

These aren't failures of SOLID.

They're simply different categories of design problems.

Understanding those recurring problems is what eventually led to the development of Design Patterns.

In This Article, You Learned

Why well-designed software still encounters new design challenges.
The categories of problems SOLID wasn't intended to solve.
Why recurring design problems appear across completely different domains.
Why recognizing the problem is more important than memorizing the solution.

One-Line Takeaway

SOLID builds strong components; Design Patterns help those components solve recurring collaboration and evolution problems.

LLD Design Patterns: What Problems Does SOLID Actually Solve?

Saras Growth Space — Fri, 07 Aug 2026 20:30:00 +0000

In the previous article, we discovered an important idea:

SOLID principles make our designs better, but they don't eliminate every design problem.

That naturally raises another question.

If SOLID isn't the complete answer, then what is it actually designed to solve?

Many developers know the five SOLID principles by name. They can even define SRP, OCP, or DIP during interviews.

Yet when asked "Why was SOLID created?", the answers are often vague.

That's because SOLID is sometimes treated as a checklist instead of a design philosophy.

Before we move into Design Patterns, let's understand exactly what SOLID helps us achieve—and just as importantly, what it was never intended to solve.

Why SOLID Was Introduced

Imagine you're building an online food delivery application.

Initially, there's only one restaurant, one payment method, and one delivery partner.

The system is small.

Adding new features is easy.

Now imagine the business grows.

New payment gateways are added.

Different delivery partners have different pricing rules.

Notifications need to support Email, SMS, Push, and WhatsApp.

Discount engines become more sophisticated.

Without a disciplined design approach, the codebase slowly starts showing familiar symptoms:

Large classes handling multiple responsibilities
Frequent modifications to existing code
Tight coupling between unrelated components
Difficult unit testing
Fear of making changes

SOLID was introduced to reduce exactly these kinds of problems.

Its goal is simple:

Help software remain maintainable as it grows.

SOLID Helps You Design Better Building Blocks

Think of constructing a city.

Every building should have a clear purpose.

Hospitals shouldn't also function as schools.

Police stations shouldn't operate restaurants.

Libraries shouldn't process tax returns.

Each building becomes easier to understand, maintain, and improve.

SOLID applies the same thinking to software.

Instead of asking:

"Can this class do one more thing?"

It encourages us to ask:

"Should this class be responsible for this at all?"

Good software isn't built by making individual classes powerful.

It's built by making responsibilities clear.

The Five Problems SOLID Addresses

Rather than memorizing five definitions, think of SOLID as five recurring design concerns.

1. Keeping Responsibilities Focused

When one class handles multiple unrelated jobs, every new requirement makes it more fragile.

SOLID encourages separating responsibilities so each class has one clear reason to change.

2. Making Software Easier to Extend

Business requirements constantly evolve.

Instead of repeatedly modifying existing classes, SOLID encourages designs where new behavior can be added through extension.

This reduces the risk of accidentally breaking existing functionality.

3. Making Inheritance Safe

Inheritance is powerful—but only when child classes truly behave like their parents.

SOLID encourages designs where replacing one implementation with another doesn't produce surprising behavior.

This keeps polymorphism reliable.

4. Preventing Bloated Interfaces

Not every consumer needs every capability.

Large interfaces force classes to depend on methods they don't actually use.

Smaller, focused interfaces reduce unnecessary dependencies and make systems easier to understand.

5. Reducing Direct Dependencies

High-level business logic shouldn't depend on low-level implementation details.

Instead, both should depend on abstractions.

This makes systems easier to test, replace, and evolve over time.

A Pattern Begins to Emerge

Notice something interesting.

Every SOLID principle is improving how individual classes are designed and connected.

They're teaching us things like:

Who owns a responsibility?
What should this class know?
What should it depend on?
How can it remain easy to change?

These are incredibly important questions.

But they're all focused on designing good components.

What SOLID Doesn't Try to Answer

Suppose your application now supports multiple payment gateways.

A new question appears:

Who should decide which payment object to create?

Or imagine users can receive notifications through Email, SMS, Push, or WhatsApp.

Now another question appears:

How should the system choose the correct notification behavior at runtime?

Or consider integrating with an external shipping provider.

Another question emerges:

How should two incompatible systems communicate without changing either one?

These aren't questions about responsibilities.

They're not questions about interfaces.

They're not questions about dependencies.

They're different kinds of design problems.

And that's perfectly okay.

Because SOLID was never designed to answer them.

Weak Thinking vs Strong Thinking

Weak Thinking

"SOLID should solve every design problem."

Strong Thinking

"SOLID solves a specific category of design problems. Other recurring problems require different design techniques."

Understanding this distinction is what separates someone who knows the principles from someone who understands software design.

Common Beginner Mistake

A common misconception is:

"If I apply all five SOLID principles, I won't need Design Patterns."

This isn't true.

Design Patterns don't replace SOLID.

They assume you've already built a good foundation using principles like SOLID.

You can think of it this way:

SOLID improves the quality of your building blocks.
Design Patterns help organize those building blocks to solve recurring architectural challenges.

They're complementary, not competing, ideas.

Interview Perspective

Interviewers rarely ask:

"What does the O in SOLID stand for?"

Instead, they often present a design scenario and observe your reasoning.

They're looking for answers like:

Why is this responsibility misplaced?
Why is this dependency problematic?
Why is this design becoming difficult to extend?

If your thinking naturally reflects SOLID principles, you won't need to force the terminology into the conversation.

The design itself will demonstrate your understanding.

Key Insight

SOLID isn't a universal solution for every software design challenge.

It provides principles for creating maintainable, flexible, and well-structured components.

As systems evolve, new categories of recurring problems emerge—and those are the problems Design Patterns were created to address.

In This Article, You Learned

Why SOLID was introduced.
The types of design problems SOLID is meant to solve.
Why SOLID focuses on building good components.
Why some recurring design problems naturally fall outside SOLID's scope.

One-Line Takeaway

SOLID teaches you how to build maintainable components—it doesn't attempt to solve every recurring design challenge in software.

LLD Design Patterns: We Learned SOLID—So Why Are We Talking About Design Patterns Now?

Saras Growth Space — Fri, 07 Aug 2026 19:30:00 +0000

If you've been following this series, you've already built a strong foundation.

We've explored how to identify responsibilities, model domains, apply SOLID principles, choose the right data structures, and think about Low-Level Design from a problem-solving perspective.

At this point, it's natural to ask:

"If I already know Object-Oriented Design and SOLID, why do I need Design Patterns?"

It's a great question.

In fact, it's the same question many developers ask when they first hear about Design Patterns. Some even assume Design Patterns are simply "advanced OOP."

They're not.

In this mini-series, we're going to discover why.

But before we learn a single pattern, we first need to understand why software engineers created Design Patterns in the first place.

We've Already Learned to Design Better Classes

Throughout this series, we've learned to think differently.

Instead of asking:

Weak Thinking

"Which classes should I create?"

We learned to ask:

Strong Thinking

"What responsibilities exist in the system?"

Instead of tightly coupling everything together, we learned to separate responsibilities.

Instead of writing one giant class, we learned to decompose problems.

Instead of constantly modifying existing code, we learned to design for extension.

SOLID principles helped us create software that is:

easier to understand
easier to test
easier to extend
less tightly coupled
more maintainable

That's a huge step toward becoming a better software engineer.

So... is the journey complete?

Not quite.

Good Principles Don't Eliminate Every Design Problem

Imagine you're building an online shopping platform.

You carefully apply SOLID.

Each class has a single responsibility.

Dependencies are injected.

Interfaces are small and focused.

Everything looks clean.

A few months later, the business team says:

"We're adding support for multiple payment providers."

Then another request arrives.

"Customers should receive notifications through Email, SMS, and Push."

A week later:

"Premium customers should use a different pricing strategy."

Nothing is technically wrong with your design.

Your classes still follow SOLID.

But new questions start appearing.

Where should objects be created?
How should different algorithms be selected?
How should unrelated components communicate?
How can we add new behavior without changing existing code?
How do we integrate with external systems?

Notice something interesting.

These aren't questions about writing better classes.

They're questions about organizing collaboration between classes.

That's a completely different level of design.

Think of Building a City

Imagine you're designing a city.

SOLID helps you design better individual buildings.

Each building has a clear purpose.

Hospitals treat patients.

Schools educate students.

Police stations maintain law and order.

Every building is well designed.

But now another problem appears.

How do people travel between them?

Where should roads go?

How should traffic flow?

How should emergency services coordinate?

Designing excellent buildings doesn't automatically create an excellent city.

The relationships between those buildings matter just as much.

Software evolves in a very similar way.

Designing good classes is only part of the challenge.

Eventually, we need to think about how those classes work together.

Design Problems Also Evolve

Early in a project, most questions look like this:

What objects exist?
What are their responsibilities?
What data should they own?

As software grows, the questions change.

Now they become:

Who should create this object?
How do I replace one implementation with another?
How do multiple objects communicate?
How do I add new features without modifying existing code?
How do I avoid repeating the same design across projects?

These are higher-level design questions.

They're not solved by adding another interface or another class.

They require recurring design solutions.

This Is Where Design Patterns Enter the Picture

Many beginners think Design Patterns replace SOLID.

They don't.

Others think Design Patterns are an alternative to Object-Oriented Design.

They aren't.

Design Patterns build on top of everything we've already learned.

Think of the journey like this:

Programming
        ↓
Object-Oriented Programming
        ↓
Object-Oriented Design
        ↓
SOLID Principles
        ↓
Design Patterns

Each step assumes you've understood the previous one.

Design Patterns don't replace good design principles.

They help you solve recurring design problems that appear after you've already applied those principles.

Common Beginner Misconception

Many developers believe:

"Once I apply SOLID, my design is finished."

Experienced engineers know something different.

SOLID gives you a strong foundation.

Real-world software keeps evolving.

New requirements appear.

Business rules change.

Teams grow.

Integrations increase.

The challenge shifts from designing individual classes to designing how many classes collaborate over time.

That's exactly the gap Design Patterns help fill.

Interview Perspective

Interviewers rarely ask Design Patterns because they want you to recite definitions.

Instead, they're evaluating something deeper.

Can you recognize that a design problem keeps appearing?

Can you explain why your current design struggles?

Can you justify introducing a new design approach?

Strong candidates don't begin with:

"I'll use the Strategy Pattern."

They begin with:

"This behavior changes frequently, so I'd like to separate it from the rest of the system."

The pattern becomes a consequence of good reasoning—not the starting point.

Key Insight

SOLID teaches us how to design better building blocks.

Design Patterns teach us how those building blocks can solve recurring design problems together.

One strengthens individual components.

The other strengthens the overall design.

Both are necessary.

In This Article, You Learned

Why learning Design Patterns after SOLID is a natural progression.
Why good class design doesn't eliminate every design challenge.
How software problems evolve as systems grow.
Why Design Patterns complement, rather than replace, SOLID principles.

One-Line Takeaway

SOLID teaches you how to build good classes; Design Patterns teach you how good classes solve recurring problems together.