Organizing Data

本篇同步发文于个人网站: 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/)

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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 exampleAssigning to an Input Parameter

Github

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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

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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 exampleMore Than One Source

Github

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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 exampleMore Than One Source

Github

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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

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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.