DEV Community: Xun Zhou

[Golang 03/30] Go: data types commonly used

Xun Zhou — Thu, 25 May 2023 05:38:20 +0000

Numeric Types:

int: Signed integer type.
int8, int16, int32, int64: Signed integer types with specific bit sizes.
uint: Unsigned integer type.
uint8, uint16, uint32, uint64: Unsigned integer types with specific bit sizes.
float32, float64: Floating-point types for representing decimal numbers.
complex64, complex128: Complex number types for representing real and imaginary parts.

Positive and negative integer

int depends on the running system. If you're running Go on 32-bit OS system, the default type for int is int32， and its range is -2^31 to 2^31-1(-2147483648, 2147483647)

Positive integer

unit8 has the range of (0, 2^8-1), i.e. (0, 255)

Boolean Type:

bool: Represents a Boolean value (true or false).

String Type:

string: Represents a sequence of characters.

Array Types:

array: A fixed-size collection of elements of the same type. The size of an array is determined at compile-time.

Slice Type:

slice: A flexible, dynamically-sized sequence of elements. Slices are built on top of arrays.

package main

import (
    "fmt"
)

func main() {
    var intA int = -12
    fmt.Printf("\nintA: %d", intA)
    //intA: -12

    var intB uint = 12
    fmt.Printf("\nintB: %d", intB)
    //intB: 12

    var floatA float64 = 98.6
    fmt.Printf("\nfloatA: %f", floatA)
    //floatA: 98.600000

    var stringVar string = "hello world!"
    fmt.Printf("\nstringVar: %s", stringVar)
    // stringVar: hello world!

    var boolVar bool = true
    fmt.Printf("\nboolVar: %t\n", boolVar)
    // boolVar: true

    var numbers = []int{0, 1, 2, 3, 4, 5}
    fmt.Printf("Size of 'numbers' is %d\n", len(numbers))
    fmt.Println(numbers)
    // Size of 'numbers' is 6
    // [0 1 2 3 4 5]

    numbers = append(numbers, 6, 7)
    fmt.Printf("Size of 'numbers' is changed to %d\n", len(numbers))
    fmt.Println(numbers)
    // Size of 'numbers' is changed to 8
    // [0 1 2 3 4 5 6 7]

    sliced := numbers[1:5]
    fmt.Printf("sliced numbers: ")
    fmt.Println(sliced)
    // sliced numbers: [1 2 3 4]

    numberArray := [3]int{1, 2}
    fmt.Printf("numberArray with size 3 and default value:")
    fmt.Println(numberArray)
    // numberArray with size 3 and default value:[1 2 0]


}

Map Type:

map: An unordered collection of key-value pairs, where each key is unique.

package main

import "fmt"

func main() {
    // Create a map to store employee names and their corresponding IDs
    // key: string, value: int
    employees := make(map[string]int)
    fmt.Printf("current size of this map: %d\n", len(employees))
    // current size of this map: 0

    // Add key-value pairs to the map
    employees["John"] = 1001
    employees["Alice"] = 1002
    employees["Bob"] = 1003
    fmt.Println(employees)
    // map[Alice:1002 Bob:1003 John:1001]

    // Accessing values from the map
    fmt.Println(employees["Alice"])  
    // Output: 1002

    // Modifying values in the map
    employees["Bob"] = 1004

    // Deleting a key-value pair from the map
    delete(employees, "John")

    // Print the updated map
    fmt.Println(employees)
    // map[Alice:1002 Bob:1004]

    // Checking if a key exists in the map
    id, exists := employees["Alice"]
    if exists {
        fmt.Println("Alice's ID:", id)
        // Alice's ID: 1002
    } else {
        fmt.Println("Alice not found")
    }

    var keys []string
    for key :=range employees {
      keys = append(keys, key)
    }
    fmt.Printf("Keys from the map 'employees': ")
    fmt.Println(keys)
    // Keys from the map 'employees': [Alice Bob]
}

[Golang 02/30] Go declare variables

Xun Zhou — Thu, 25 May 2023 04:18:16 +0000

package main

import (
  "fmt"
)

func main() {
  // declare a variable with value "hello"
  var a = "hello"
  fmt.Printf("\na: %s", a)

  // shortcut for "var ab string"
  // it declares a variable named "ab", 
  // and auto-detect its type and assign the value "hello" to it.
  ab := "hello"
  fmt.Printf("\nab: %s", ab)

  // declare a variable with explicit type
  var abc string= "hello"
  fmt.Printf("\nabc: %s", abc)

  // declare multiple variables with type "int"
  var b, c int;
  fmt.Printf("\nb: %d, c:%d", b, c)

  // declare multiple variables and assign them the values
  // the types will be auto-detected
  var d, e = 1, "golang"
  fmt.Printf("\nd: %d, e: %s", d, e)
}

It prints the following content:

a: hello
ab: hello
abc: hello
b: 0, c:0
d: 1, e: golang

Summary

In Go, we can declare variables using the var keyword or its shortcut :=.
Golang will assign the default value to the variables, which are not initialized.
For example:

string default: empty string
int default: 0
bool default: false

[Golang 01/30] Go pointer and variable

Xun Zhou — Wed, 24 May 2023 16:03:44 +0000

Pointer in Golang is a variable which is used to stores the memory address of another variable. The memory address is always found in hexadecimal format, i.e. 0xFFAAF etc.

Most important operators we will used in pointer are:

operator *
- declare pointer variable
- access the value stored in that address
operator &
- return the address of a variable

package main

import (
    "fmt"
)

func main() {

    // declare a variable
    var myVar int = 5

    // declare a pointer variable for type "int"
    var pointerVar *int

    // assign the address to that pointer variable
    pointerVar = &myVar

    fmt.Printf("\nAn integer %d is assigned to 'myVar', its location in memory: %p", myVar, &myVar)
    fmt.Printf("\nThe Value at memory location %p is %d", pointerVar, *pointerVar)

    // overwrite the content at the address
    *pointerVar = 100
    fmt.Printf("\nThe Value at memory location %p is changed to %d", pointerVar, *pointerVar)
    fmt.Printf("\nThe Value of 'myVar' with same address is changed to %d, too.", myVar)
}

It prints the following content:

An integer 5 is assigned to 'myVar', its location in memory: 0xc0000b8000
The Value at memory location 0xc0000b8000 is 5
The Value at memory location 0xc00001c030 is changed to 100
The Value of 'myVar' with same address is changed to 100, too.

Summary

Here & is used to get the address of the variable myVar, so &myVar and pointerVar has the same value 0xc0000b8000.
* symbol is used to read the value at memory address 0xc0000b8000, so *pointerVar shows the same content 5 as myVar.

Web3: smart contract

Xun Zhou — Mon, 12 Sep 2022 07:00:21 +0000

In web3, we store a contract, an actual agreement, and this doen't just meana digitalized PDF. It it a mini program with a predefined list of rules to very specifically control the business transactions. And what makes a smart contract smart is that once on the blockchain, it will be executed automatically, based on those rules. Because smart contact is written in code, it requires no intermediary to make them happen, they're fully automactic. Like the other things in blockchain, once it's placed there, it can't be changed.

IBM "Smart contracts are digital contracts store on a blockchain that are automatically executed when predetermined terms and conditions are met. They typically are used to automate the execution of an agreement so that all participants can immediately certain of the outcome without any intermediary's involvement or time loss."
https://www.ibm.com/topics/smart-contracts

Microsoft "a smart contract is a program that's stored inside a blockchain. Smart contracts extend blockchain from data to code. They represent an agreement between parties. The agreement is coded, and when an action happens, the code runs and provides a response. All of the terms and conditions of the contracts are programmatically defined. ... Smart contracts run on their own, send events that trigger state transistions, and call functions. They're pefect for blockchain technology because they allow people who don't know one another to do business in a securely specified way that requires no middleman. ... Smart contracts are most commonly used with Ethereum. It allows smart contacts to be defined to help facilitates the transfer of digital assets, like ether."
https://docs.microsoft.com/en-us/training/modules/blockchain-solidity-ethereum-smart-contracts/2-smart-contracts

wikipedia "A smart contract is a computer program or transaction protocol that is intended to automatically execute, control or document legally relevant events and actions according to the terms of a contract or an agreement. The objectives of smart contracts are the reduction of need for trusted intermediators, arbitrations costs, fraud losses, as well as the reduction of malicious and accidental exceptions. Smart contracts are commonly associated with cryptocurrencies, and the smart contracts introduced by Ethereum are generally considered a fundamental building block for decentralized finance(DeFi) applications." https://en.wikipedia.org/wiki/Smart_contract

Use D-MVC Pattern in Symfony Application

Xun Zhou — Sun, 24 Jul 2022 11:44:43 +0000

🗣 Our story

This is about the journey to a lightweight software design for a complex conference management system.

The story started with:

I am going to design a conference management system. It should contain different domains: user management, tweets and rating, schedule talks, registration & SSO. The development should take the domains into consideration.

See the design overview of conference management system

🤯 Our challenge

Most of our developers might have less experience with software design, especially complex systems. The architecture such as Onion architecture, Hexagonal Architecture or Clean Architecture might be overkill for most of them who have less knowledge about design. But they all know well MVC pattern, which is actually native pattern used in a standard Symfony project.

😎 Bingo ! D-MVC Architecture

I came to the idea to design this mixed project structure, so that the developers with less experience can follow and understand the architecture as well.

MVC is most well-known architecture which is widely used in ruby on rails and Symfony framework.

But what is D-MVC? 😱
In fact, it is just based on the MVC principle, but inspired by common-used pattern duck-redux from Frontend-world. read more on what is redux ducks?

Ducks is a modular pattern that collocates actions, action types and reducers, which are used in redux implementation
Because the structure of the project looks like the ducks in the row, see the image below :D

the guideline in duck-MVC: we built different modules(i.e. ducks) that are strictly designed and implemented in MVC pattern.

🚀 Every Developer knows well `MVC`

Because every developer knows well MVC and there is no need to coach them. We are able to get started easier and faster.
To make the project more familiar with standard Symfony project, I kept the View layer as default in Symfony framework, i.e. all views are still located in /templates folder.

Each duck should contain just the three parts:

Controller: controller the web request or API request
Model: all domain specific services, models, which are common used by the controller.
View: in fact, they are located in /templates folder (This is standard way from Symfony framework. I kept the thing as simple as possible. Sure, it can be moved directly within a duck :: user folder, too.)

Based on this D-MVC approach, we are able to build different modules for the business domains. It can be very easily scaled with more modules.

Schedule: module to manage the schedule of talks
Security: module to manage authentication and SSO
Tweet: module to manage the conference tweets and ratings
User: module to manage the users
... other modules

✅ Getting things done

the cool part of this approach is the possibility to maximize the team velocity with less knowledge in software architecture. Additionally, I have still the following important things involved in this approach:

Domain

I don't divide the domains into pieces and distribute them in the different ducks. Because most of them are shared among the different domains. Putting them together will reduce the cost of maintenance and the code can be shared friendly among the ducks.

The domain folder contains the most important domain related stuffs:

Entities: the doctrine entities
Validations: the implementations of the business rules
Value Objects: the domain specific value objects

👥 Conclusion

This solution is a good approach for a team, which has less architecture knowledge. It can maximize the team effort without taking too much time in thinking it over, where should I put the files. The developer should just follow the basic principles, which they learned in the past MVC projects. It should work.

Additionally, we have still some valuable wins:

scalability: Project can be scaled very easily. It will still keep the project in the very clear structure, if the project domains become complex.
simplicity: there is no magic in this solution, but very pragmatical. Every developer can get started very easily with this setup and less design knowledge is required.
domain-driven: because we try to build the small ducks for the special domains. It help both the business and development to track the problem as quick as possible in the target duck area.
Mobility: Each duck has the standard MVC structure. The code can be transformed very easily into micro-service, if it is needed.

This article might not be able to be used as a solution template, because there is still something that are not included and explained. But it can be an inspiration for finding a pragmatic solution for Symfony web development. If it will help u or if you have any question, feel free to write the comments or get the contact directly with me.

3x essential tests in Symfony application

Xun Zhou — Sun, 24 Jul 2022 09:33:34 +0000

You wanna be a good Symfony developer, so give the time to master the following three testing in Symfony application.

Type	TestCase (common used)	description
Unit	`TestCase`	It ensures that individual units of source code (e.g. a single class or some specific method in some class) meet their design and behave as intended
Functional	`WebTestCase`	It checks the integration of the different layers of an application (from the routing to the views).
Integration	`KernelTestCase`	It tests a larger part of source code as integrated components. It uses generally the Symfony Kernel to fetch a service from the dependency injection container.

The simplest way to start any type of tests, is to use maker bundle:


# install the maker bundle
❯ symfony composer req --dev orm maker

# install the test bundle
❯ symfony composer req --dev symfony/test-pack

❯ symfony console make:test

# Which test type would you like?:
#  [TestCase       ] basic PHPUnit tests
#  [KernelTestCase ] basic tests that have access to Symfony services
#  [WebTestCase    ] to run browser-like scenarios, but that don't execute JavaScript code
# >

5 ways to give people a moment to remember

Xun Zhou — Sat, 23 Jul 2022 13:52:03 +0000

The key is to give them something to remember. Whether you're delivering a presentation virtually or in person, your listeners will not recall every word you say. They'll remember moments.

Great communicators intentionally design memorable moments by using some of the following tactics.

🎯 Tell stories

Share personal stories that are relevant to the theme of your presentation.

🎯 Offer surprising statistics

Find one number that grabs your audience's attention.

🎯 Create analogies

A well-chosen analogy speaks volumes.

Plan surprise reveals

Your message doesn't have to change; just change the way you express it.

🎯 Show Photos, images and videos

Picture superiority effect.

Above all, people do not pay attention to boring things. Give your audience something to remember, like a story or a surprise they didn't expect.

Read the original article here

Why do you should protect the scrum sprint

Xun Zhou — Sat, 23 Jul 2022 13:30:35 +0000

Today I shared my agile development experience with my team. The presentation was about the difference between KanBan and Scrum.

One of import thing I pointed out in the presentation was about "sprint protection".

❓ "Sprint is protected!?" but what should we do as next, if we are going to finish the tickets before time box?

👉 The sprint is generally protected, after the team started the sprint. If we do NOT have special reason, we should not just simply pull the new tickets from backlog, just because Project managers or customers want to have them. In fact, many teams do it in this way.

In my opinion, there are plenty of things to do in the rest of your sprint days instead of adding new Tickets to current sprint.

I wanna give you some examples:

✅ get started with the technical debts

Some technical optimisation might not be very interesting for PO/PM, but it is very important for a maintainable software product. For example, well structured dashboard, monitoring. You should use this opportunity to work on them.

✅ do internal training

The team should grow up together in scrum. Internal coaching for agile development, special knowledge sharing, and pair-programming for special dojo can help the team to improve their skills. The growth in technical skills in a team will bring directly impact on the velocity. The mentoring process will help you in team building and build trust among the developers.

✅ organise small refinement meetings

The team can use the time to organise additional refinement meeting to improve backlog.

✅ R&D

Do research and development in the area, in which we have still less knowledge. Be innovative and try something out. A new testing framework, or new coroutine programming approach, and so on.

❌ Don't change the sprint Goal, if you have NO special reasons to do that. But use the rest of sprint time proactively for the things I mentioned above. Scrum is about the #teamculture, #workflows, and #increments. The increments are not only about the deliverable increments for the customers, but also about the growth within the scrum team.

12x things make you a better software engineer

Xun Zhou — Sat, 23 Jul 2022 13:23:26 +0000

I love coding and enjoy thinking in design and architecture. I give always my best to do the best as I can.
In my opinion, the following things make a good software engineer:

🎯 master the essential tools

you should be professional to use the essential dev tools, such as editor, IDE, CLI, which you are using daily for the development. So, find the time to train yourself to master the hotkey, best practice for the dev tools.

🎯 master the essentials patterns/architectures

As a good software engineer, you need the fundamental knowledge about the essential design patterns and software architectures. This will help you to understand the other's source code or software product faster as possible. It will build the fundament to design a good software in your mind.

🎯 Pairing with more experienced software engineer

Pair-programming is the most efficient way to improve the coding skill in the short term.

🎯 less copy and pasting

Stack-Overflow!? Yes, I do. But do less copy and pasting, if you wanna be a better software engineer. Try to write the tests, or rename the variables or refactor the original code, if you HAVE TO do copy and pasting.

🎯 read or write min 30. mins every day

As software engineer, insisting on reading and writing.

🎯 use TDD as design tool

Yes, TDD as design tool. Early very difficult, but big impact in the future.

🎯 watch tech talks

The world is changing. And it changes faster as you image. So stay hungry and stay foolish. P.S. be like a child, not a senior 😀

🎯 keep open-source mindset

Try to be involved in open-source software projects; share your best practice, code snippets or packages in the community. Don't own the code alone by yourself, but share them.

🎯 make side-projects

Do something different and make side-projects.

🎯 find a great mentor & be a great mentor

you should have a mentor to guide you, so that you will get the maximal performance in the shortest time. "Try to teach others and share your experience from beginning on. When you are a junior you can mentor students, when you have already some experience you can mentor a junior." You will have the deeper understanding on what you are teaching and mentoring. It help both parties, if you are doing a mentoring well.

🎯 learn to communicate well

Software engineer shares the value to the community and communicate well. So go out of the comfort zone and learn to communicate well.

🎯 think beyond the code, and think like designers

Designers care about the user experience, good styling and product value. Yes, we do! We care about the good design and architecture, and the business value and the end-users.

If you agree with one of these points, take it and do it well in the coming days. :)

How do I organise the documents on my company MacBook

Xun Zhou — Sat, 23 Jul 2022 13:23:02 +0000

In the past days, I got the new company MacBook M1 Max to replace another old MacBook. Again I have to organise and synchronise my documents, softwares, and projects. Sure, many different configurations.

Yes, I know there is the fastest way to synchronise two MacBooks via iCloud or time machine. But sometimes, I do not really do a 1🔛1 clone between two laptops. Because I prefer to have a fresh and clean start on the new machine. So my favorite way is to use the company certificated cloud solution "OneDrive" to synchronise my documents.

1. create a good structure to archive the documents for cloud storage

`organisation`

I manage all files related to the company organisation and HR management.

`conference`

I manage all documents including slides, books, talks, screenshots, which are related to the conferences, workshops.

`side-projects`

I did some side-projects in the company innovation hours. Besides the project source codes, there are some mind-maps, project planning, documentation, articles, which are related to those projects, but are fit for code repositories. I would like to put them here.

`software`

Some extension and software, which I build by myself.

`book`

Here is the home of all my Ebooks, and PDFs.

`automators`

I use a lots automators for MacOS, which can be used to do a batch of tasks for my daily work. For example: I wrote an automate to open automatically the editor dev.to to write a new article in a second.

`presentation`

I do a lots of presentations for internal coaching for our junior developers. I download some presentations from the others to learn some new stuffs from them. Here will be the good place for all of them.

`private`

as shown in the name, there are some private document, such as my certificates for Agile ScrumMaster, Agile Developer, and so on.

`work`

In this folder, I manage all the documents which are related to the working projects at the company.

`learning`

I have collected some learning stuffs, such as tutorial videos for golang, symfony, rust. I would like put them here in this learning area.

2. create a synchronisation plan

I configured cloud driver OneDriver to synchronise my documents folder. But I excluded the following folders:

software: some of them are too large
learning: most of tutorial videos are large than 800MB

3. Synchronise the documents to the new MacBook

It takes about one hour to have all the documents synchronised from OneDriver. I chose the lunch break to start the synchronisation. It will never affect my work and in the mood.😀

I would like to write another article soon to share my experience and I wanna show you how I installed the software packages on my bland new MacBook.

10 things you should do to become a Project manager

Xun Zhou — Tue, 12 Jul 2022 20:03:58 +0000

1. Learn as much as you can about product management

you should learn as much as you can about product management white you are still a software engineer.

2. Stick to your domain expertise

You should stick to the domain expertise at the beginning.

3. Keep and strengthen your SQL knowledge

As a product manager, you constantly need to validate your assumptions with qualitative and quantitative data.

4. Skills to use UMLs and User flows

Be a professional for UMLs and user flows. It will help you understand both development and business well.

5. Keep open-source mindset

Keep on sharing knowledge generously.

6. Make side-project

Prioritising learning above programming.

7. Hackathons

Given the time constraint hackathons often just focus on feasibilities test, not desirability test.

8. Become a good writer

A skill to master is to learn to write good notes and documentation. Convert notes into action items is the next stage.

9. Keep away from solution discussions

To be a PM, you should learn to give the authority about the solution to the developers. The duty of PM is to describe the "why" and "What".

10. Get out of GitHub

starting the focus on identifying the user needs and business requirements and learning how to write great user story. GitHub will distract your focus and will ultimately harm the trust as PM among the developers.

This is a summary of this nice talk by Product People. You can check this video on https://www.youtube.com/watch?v=4hnu4FM6qYY

Best Practice: Makefile

Xun Zhou — Sun, 26 Jun 2022 18:44:14 +0000

Download My Makefile on GitHub Gist

I use Makefile for most of every my project, both at work and in side-projects.
It let you just create very easily task group in a Makefile, which you can execute them via make command.

My best practices are the following:

Minimal config

I remove all unnecessary definition which might make noise in the Makefile. Now it has just 6 lines to configure and define the templating of my favorite Makefile.



SHELL := /bin/bash

help:
    @grep -E '^[0-9a-zA-Z_-]+:.*?## .*$$|(^#--)' $(MAKEFILE_LIST) \
    | awk 'BEGIN {FS = ":.*?## "}; {printf "\033[32m %-43s\033[0m %s\n", $$1, $$2}' \
    | sed -e 's/\[32m #-- /[33m/'

Help: this code block defines the templating for the task group and its tasks and I used it in every my makefile.

Group your task

With Prefix #--, you are able to define the title of task group. We can organise the relevant tasks in the same task group.



#-- Docker

this will define a task group with title name Docker

Add task always the a task description

by using prefix ## description of this task, we can add the description to each task.
The following code defines a task group Docker with a single task clean, which triggers four commands to clean up the docker resources.


 bash  
clean: ## clean up all docker resources
  docker-compose stop
  docker container prune -f
  docker volume prune -f
  docker network prune -f

each command should begin with a Tab, for example, there is always a Tab before the command docker-compose stop.

Simple start

By using make, you can show the list of all defined task groups in Makefile
By using make clean, you can execute the task clean under the task group docker

See the final result in the terminal:

Download My Makefile on GitHub Gist

DEV Community: Xun Zhou

[Golang 03/30] Go: data types commonly used

[Golang 02/30] Go declare variables

Summary

[Golang 01/30] Go pointer and variable

Summary

Web3: smart contract

Use D-MVC Pattern in Symfony Application

🗣 Our story

🤯 Our challenge

😎 Bingo ! D-MVC Architecture

🚀 Every Developer knows well MVC

✅ Getting things done

Domain

👥 Conclusion

Additionally, we have still some valuable wins:

3x essential tests in Symfony application

5 ways to give people a moment to remember

🎯 Tell stories

🎯 Offer surprising statistics

🎯 Create analogies

Plan surprise reveals

🎯 Show Photos, images and videos

Why do you should protect the scrum sprint

✅ get started with the technical debts

✅ do internal training

✅ organise small refinement meetings

✅ R&D

12x things make you a better software engineer

🎯 master the essential tools

🎯 master the essentials patterns/architectures

🎯 Pairing with more experienced software engineer

🎯 less copy and pasting

🎯 read or write min 30. mins every day

🎯 use TDD as design tool

🎯 watch tech talks

🎯 keep open-source mindset

🎯 make side-projects

🎯 find a great mentor & be a great mentor

🎯 learn to communicate well

🎯 think beyond the code, and think like designers

How do I organise the documents on my company MacBook

1. create a good structure to archive the documents for cloud storage

organisation

conference

side-projects

software

book

automators

presentation

private

work

learning

2. create a synchronisation plan

3. Synchronise the documents to the new MacBook

10 things you should do to become a Project manager

1. Learn as much as you can about product management

2. Stick to your domain expertise

3. Keep and strengthen your SQL knowledge

4. Skills to use UMLs and User flows

5. Keep open-source mindset

6. Make side-project

7. Hackathons

8. Become a good writer

9. Keep away from solution discussions

10. Get out of GitHub

Best Practice: Makefile

Minimal config

Group your task

Add task always the a task description

Simple start

🚀 Every Developer knows well `MVC`

`organisation`

`conference`

`side-projects`

`software`

`book`

`automators`

`presentation`

`private`

`work`

`learning`