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Refactor Conditionals by Decomposing Conditional

Legacy Coderetreat: Part 16 – Refactor Conditionals by Decomposing Conditional

Refactor conditionals by Decompose Conditional

Blog post series

This blog post is part of a series about legacy coderetreat and legacy code techniques you can apply during your work. Please click to see more sessions about legacy code.

IF-THEN-ELSE-END_flowchart

Purpose

We often see code with conditionals that are hard to understand. The purpose of this technique is to make the code look readable by extracting a function with the condition. It will be easier to test the code if the condition is extracted and injected as a dependency.

This technique is useful when having good variable names is not enough to explain the condition. We can have some of the following reasons for wanting to extract a function with the condition:

  • The condition is duplicated in several parts of the class
  • The condition is duplicated along different classes
  • Test the condition in isolation, because of its complex nature
  • Test the code without understanding how the conditions work (inject conditions as stubs)

 

Legacy Code Extract Class

Legacy Coderetreat: Part 12 – Extract class

Extract Class

Blog post series

This blog post is part of a series about legacy coderetreat and legacy code techniques you can apply during your work. Please click to see more sessions about legacy code.

Purpose

When working with existing code we need to look at the responsibilities of existing classes. If one class is too big, we need to extract new classes from that initial class. A class too big means that it’s not respecting the Single Responsibility Principle.

Extract Class
Extract Class
Legacy Code Extract and Override

Legacy Coderetreat: Part 8 – Extract and Override

Extract and Override

Blog post series

This blog post is part of a series about legacy coderetreat and legacy code techniques you can apply during your work. Please click to see more sessions about legacy code.

Purpose

Almost always when needing to test existing code we bump against dependencies that make the system untestable. This technique is useful to extract the static dependencies. After that we can use dependency inversion in order to be able to really test the systems.

With this technique we can transform untestable systems into testable systems, step by step. The steps are small because we want to enable safety while changing the code.

Extract and Override
Extract and Override