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Speculative Generality

"Speculative Generality" is identifying "Just in Case" code. It’s when you add bells and whistles to your code to handle cases that might happen in the future, but currently don't exist.

Arguments are added to functions that are always passed the same value. Abstract classes are created that have only one subclass. Interfaces are defined for things that only have one implementation. It’s over-engineering at its finest.

"YAGNI: You Aren't Gonna Need It."

Signs of the Smell​

  • Methods with unused parameters.
  • Class hierarchies that seem pointless (single subclass).
  • Methods named processAnything, handleGenericInput when simple names would do.
  • Code that handles "future requirements."

Reasons of the Smell​

Over-Enthusiasm: "I bet we’re going to need this later, so I’ll build it now to save time!" (Spoiler: It rarely saves time). Lack of Focus: Focusing on a framework rather than the immediate business problem.

Refactoring Recipe​

  • Collapse Hierarchy
  • Inline Class
  • Remove Parameter
  • Rename Method

Collapse Hierarchy​

If you have an abstract class AbstractAnimal but only one actual animal Dog, just merge them.

Before:

abstract class AbstractVehicle {
    abstract void drive();
}
class Car extends AbstractVehicle {
    void drive() { ... }
}
// No other vehicles exist

After:

class Car {
    void drive() { ... }
}

Remove Parameter​

If a parameter is always passed as null or 0 or true, remove it.

Before:

// "isTest" is always false in production code
public void save(Data d, boolean isTest) { ... }

After:

public void save(Data d) { ... }

References​