Singular or plural verb in function name? [closed]

Question

Take Java standard library as an example, why is not Object.equals called Object.equal? And why is Object.clone used singular from, not Object.clones?

Why do I see almost all people use getXXX and setXXX in reading and setting properties of an object, not gets or sets?

Answer 1

Those method names are verbs, not nouns. equals is the third-person form of the verb "equal" (likely interrogative -- in languages that support non-alphanumeric characters in method names it's often called equals?), and clone is the second-person imperative form of the verb "clone" (you're ordering the object: "clone yourself!").

In general, you use interrogative verbs for methods that query information about the object state relative to another (equals, contains, hasXXX...), imperative verbs for "action" methods (methods that ask the object to perform some task, e.g. clone, add, show... Very often these methods don't return anything), and nouns for methods that query information about the object's state without referencing anything external (e.g. length, intValue, keys). Note that those nouns can be singular or plural depending on what the method returns: singular for something that can only be singular (length), plural for something that can return a list/map/other container (keys).

Getters are a special case, where you use an action verb (get) to "tag" these methods as getters, and for symmetry with setters that use set.

Also, getters/setters are a workaround for the lack of properties in C++ and Java. In a language without that weakness, they don't exist: you use properties instead, and those are nouns.