Welcome to the third lesson of our course, where we explore the concept of the Parameter Object to address a common code smell: complex function signatures. Throughout this course, we work on eliminating code smells to enhance the readability, maintainability, and scalability of your codebase, with a strong emphasis on Test-Driven Development (TDD) in Scala 3.
In our previous lessons, we addressed code smells like duplicated code by using Extract Method to manage long methods. Today, we tackle the code smell associated with long parameter lists and introduce the Parameter Object as an effective solution. We will leverage Scala's object-oriented features and (hypothetically) ScalaTest for our tests. Remember, the TDD cycle—Red, Green, Refactor—guides us in maintaining and improving our code while ensuring existing behavior remains valid.
Long parameter lists are considered a code smell because they complicate method signatures, making the code harder to read, maintain, and test. This complexity arises from several issues:
-
Readability: A method with many parameters is difficult to interpret without extensive documentation.
-
Maintainability: Adding or removing parameters forces updates across the codebase, risking mistakes in existing calls.
-
Error-Prone: Similar or numerous parameters increase the chance of mix-ups, even with strong typing.
-
Testing Challenges: Writing and maintaining tests for a long list of parameters becomes tedious, potentially discouraging comprehensive testing.
-
Lack of Cohesion: A long list can indicate that the method is handling multiple responsibilities, violating the single responsibility principle.
By recognizing long parameter lists as a code smell and refactoring them into a , we reduce complexity and make our methods more robust and understandable.
