Introduction & Context Setting

In our previous lesson, you learned how to eliminate duplicated code through function extraction and the refactoring of magic numbers. This lesson builds upon that foundation by introducing another crucial refactoring technique: the Extract Method. This technique is vital for transforming long, complex functions into smaller, more manageable ones, enhancing both readability and maintainability. As we delve into this lesson, remember that our goal is to follow the Test-Driven Development (TDD) workflow: Red, Green, Refactor. This iterative cycle ensures that we can leverage our tests when refactoring to confirm that we have not changed anything about the behavior. If you change behavior, it is not a successful refactor.

Understanding the Problem with Long Methods

Long methods are a code smell that can hinder efficient development as they often become difficult to understand, test, and maintain. A method might be considered long if it handles multiple responsibilities, making the code harder to track and debug. This complexity can impede our ability to effectively employ the TDD cycle, as isolated testing of functionalities becomes more challenging. Our task is to identify such cumbersome methods and employ the Extract Method technique to break them down into smaller, focused sub-methods, each with a single responsibility.

An Example of a Long Method

Take a look at the following function. Notice how it is not only long, but it is also responsible for doing a lot of things. Can you identify the different tasks this function is handling?

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