Test whether another object is equal to this function.
System-created function objects are only equal to other functions.
Two function objects are known to represent the same function if
- It is the same object. Static and top-level functions are compile time constants when used as values, so referring to the same function twice always give the same object,
- or if they refer to the same member method extracted from the same object. Extracting a member method as a function value twice gives equal, but not necessarily identical, function values.
Function expressions never give rise to equal function objects. Each time a function expression is evaluated, it creates a new closure value that is not known to be equal to other closures created by the same expression.
Function by having a
call method should have their
hashCode depending on the object.
bool operator ==(Object other);