Speculative Generality
When you find codes for future requirements that are not currently needed.
Sign of Smell
Speculative Generality is a code smell that occurs when code is written to handle potential future requirements or scenarios that may never actually be needed. It is similar to the Dead Code smell, which refers to unused code that serves no purpose in the current implementation. While both of these smells involve unused code, but they arise for different reasons.
When we compare these two smells closely, we can find the following differences.
Nature: Speculative Generality refers to over-engineering and creating unnecessary complexity, while Dead Code refers to unused or obsolete parts of the codebase.
Timing: Speculative Generality often involves preemptively adding unnecessary abstractions or features, while Dead Code typically arises from changes in the codebase over time.
Impact: Both code smells can make the codebase harder to maintain and understand, but Speculative Generality introduces unnecessary complexity, while Dead Code is more about cleanliness and removing unnecessary clutter.
Mitigation: Speculative Generality can be mitigated by following the YAGNI (You Aren't Gonna Need It) principle and avoiding over-engineering. Dead Code can be mitigated by conducting regular code reviews and using static code analysis tools to detect and remove unused code.
The main difference between the two code smells is that Speculative Generality may not really be “unused code” if you use static code analysis tools to detect it in your codebase. However, from a business or requirement perspective, it can be considered unused code.
This confusion is based on the definition of "unused code." Dead Code refers to code that is unused by other code. On the other hand, Speculative Generality refers to code that is currently unused from a business or requirement perspective.
One last funny fact is that, unlike other smells, Speculative Generality is often created by experienced programmers who sometimes engage in over-engineering.
Reason of Smell
Here are some reasons why Speculative Generality is considered a code smell:
Reduced Readability: Code that includes unnecessary abstractions or layers can become less readable. It can be challenging to follow the logic and flow of the code when it is overly abstracted, making it harder to debug and maintain.
YAGNI Violation: YAGNI stands for "You Aren't Gonna Need It," which is a software development principle that advises against adding functionality or abstractions until they are actually needed. Speculative Generality violates this principle, as it adds complexity and features that may never be required, wasting development time and effort.
Increased Complexity: Unnecessary abstractions, classes, methods, or features add complexity to the codebase. This complexity can make it more challenging for developers to understand the code and can increase the likelihood of bugs and maintenance issues.
Confusion for Developers: Speculative Generality can confuse developers who may struggle to determine which parts of the code are essential and which are speculative. They may not be sure which classes or methods to use, leading to inconsistency in code design.
Bloat: Unnecessary code increases the size of the codebase, which can negatively impact performance, increase compilation times, and consume more storage. It can also make the codebase less efficient and slower to develop.
Risk of Misalignment: Code that is overly generalized may not align with actual future requirements if they do eventually arise. This means that the code created speculatively may not actually serve its intended purpose when those requirements become relevant.
Maintenance Overhead: Code that is overly generalized or abstracted requires more maintenance. Developers may need to update or fix code that was created in anticipation of future requirements but is not currently used. This can waste time and effort.
Refactoring Recipes
The refactoring skill "Rename Method" is listed in the Smells to Refactorings Cheatsheet. However, I personally don't think it's a good match for the Speculative Generality smell.
The other three skills are exactly the same as the countermeasure for the Dead Code smell.
Collapse Hierarchy
Rename MethodRemove Parameter
Inline Class
Collapse Hierarchy
When we find that a class is doing very little and it is a subclass, we can merge it with its superclass.
Remove Parameter
When we notice that a parameter is currently not used, we should consider removing it.
Inline Class
When we find that your class is doing almost nothing, we can definitely consider moving all the features from the class to another one.
Reference
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