Organizing Data

本篇同步发文於个人网站: Organizing Data

This article references the chapter 9 ” Organizing Data ” of Refactoring: Improving the Design of Existing Code (2nd Edition). Author had highlighted many important refactorings in this chapter.

I use .NET C# to practice with these refactorings and upload to Github.

(Photo from Pixabay: https://pixabay.com/photos/cabinet-drawer-wood-catalogue-3283536/)

Split Variable

Tips

• Loop variable and collecting variable are special. They are assigned value many times.
• Other variable is responsible for one thing. It should be assigned value one time.
• If some variable is assigned many times, we should split it into different variables.

Examples:

• A simple example
• Assigning to an Input Parameter

Github

Rename Field

Tips

• A field with good naming makes the developer clever about what the code does.
• Field and accessors (getter/setter) namings are important.
• If a record is still not encapsulated, use Encapsulate Record.

Examples:

• A simple example

Github

Replace Derived Variable with Query

Tips

• We should minimize the scope of mutable data at much as possible.
• Use this skill to avoid “We update the source data but we forget to update the derived variable”

Examples:

• A simple example
• More Than One Source

Github

Change Reference to Value

Tips

• A value object is immutable. We can transfer this object into other logic without caring about modifying the object’s data.
• If an object can be shared between many objects and they can see its modification, it should be a reference object.
• Value object usually implements equals function.

Examples:

• A simple example
• More Than One Source

Github

Change Reference to Value

Tips

• If a shared Value Object data needs update, we need to find all data copies and update them. Change it to Reference Object and the object’s update reflects on all clients.
• Build a Repository to manage the reference object. All clients find the reference objects by the repository.

Examples:

• A simple example

Github

Conclusion

This chapter introduces me how to organize data. In ASP.NET MVC development, I have used Service/Repository pattern to manage my data source. And I used the LINQ to perform Replace Derived Variable with Query. I have grown up to write better code when I study this refactoring chapter. If you want to learn detailed motivation and mechanics, study the chapter 9 ” Organizing Data ” of Refactoring: Improving the Design of Existing Code (2nd Edition). and it improves our programmer’s ability.