Introduction
4 years later, when I started programming I used to write code and just care about the results mainly Its working How it's intended to be stance. But as time passed I realized that whenever I want to add a new functionality within, it becomes nearly impossible for me.
However Rails defaults enable us to stick with OOP principles and good practices, but as codebase grows you have to be a champion to hold up things properly!
So I have to compromise and search for escape routes. My bad. Being pro-active and habit of thinking to extend the genre is what I'm missing. By time I learnt from different experiences, features, other people's code and mainly from Google (How can I miss this!)
Why we need Refactoring?
As I described above that it becomes hard to extend features, add new stuff but mainly you lose the control of your codebase. You become a slave of an unknown compelling force established within your app. Produced by your bad code and mis management.
Just think about big tech giants and social media apps, how code is being managed and scaled to reach a bigger audience. You'll get the answer for sure!
Jumping into the Playground
Today I'm going to share my initial 5 steps approach to refactor a bad piece of code. It can be a starting point for those who don't have an idea about Where to start?.
Lets start this!
As an example, we'll discuss this controller action in Rails which have code smells. It enables admin to assign user a specific subscription membership group.
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1: Dry run each line of code, understand meanings?
I have added comments against each line. See
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2: Identify responsibilities with Divide & Conquer rule
- Authorization check for user's role
- Query user from db and figure out user old membership and new group for further addition
- Update user with new attrs
- Send membership email
- Perform subscription expiry job
- Handle failure case of #update
- Handle failure case of authorization
3: Extract methods by Single Responsibility Principle
The single-responsibility principle (SRP) is a computer-programming principle that states that every module, class or function in a computer program should have responsibility over a single part of that program's functionality, and it should encapsulate that part.
In accordance with responsibilites obtained in Step 2. I've added seperate methods. Each doing its own thing.
check_user_role! depicts authorization check, continue only if user is an admin otherwise redirect. The ! at the end describes that its going to follow-up immediately
grab_user_and_associated_group find user, get membership names, group and expiry date. Here I switched local variables with instance variables to manipulate them among micro actions. Provided the fact we can also use them inside views.
user_params prepares hash to pass inside update call
update_user updates user and call forward_emails_then_set_job. It has an else case to describe if something goes wrong.
forward_email_then_set_job calls mailer and job classes respectively. For sake of simplicity, I'm skipping discussion for them!
Notice about usage of redirect_back in this context, instead of using redirect_to with request.referrer You can find it here
4: Filter out performance gaps and fill them
If you notice down, there is a performance gap inside forward_email_then_set_job. The problem is deliver_now and perform_now. When we have a queue backend like Sidekiq in place, its essential to configure queues which can hold up jobs to perform one by one. deliver_now halts this priority queue and we can face the situations where jobs received at same time instant would be dropped, thus creating load on queue backend.
For the solution, I've used deliver_later and perform_later which takes care of priority queue. Jobs are processed one by one, providing minimal drop chances and optimized queue backend
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5: Put all pieces and ask yourself Is it improved?
The answer can be Yes or No. But the new version would be better than worst. A stable form!
Refactoring is costly if not done from the start. Its a habit towards self improvisation and better understanding of code.
I haven't came up with a perfect version. There are certain improvements we can do here. I would like to hear from you guys. Do Share and Like if you find it useful ..
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