[function.objects.general] (original) (raw)
A function object type is an object type ([basic.types.general]) that can be the type of thepostfix-expressionin a function call ([expr.call], [over.match.call]).194
A function object is an object of a function object type.
In the places where one would expect to pass a pointer to a function to an algorithmic template ([algorithms]), the interface is specified to accept a function object.
This not only makes algorithmic templates work with pointers to functions, but also enables them to work with arbitrary function objects.