12 Overloading [over]

A function call operator function is a function named operator() that is a non-static member function with an arbitrary number of parameters.

It may have default arguments.

For an expression of the form

postfix-expression ( expression-list${}_{opt}$ )

where the postfix-expression is of class type, the operator function is selected by overload resolution ([over.call.object]).

If a surrogate call function for a conversion function named operator conversion-type-id is selected, the expression is interpreted as

postfix-expression . operator conversion-type-id () ( expression-list${}_{opt}$ )

Otherwise, the expression is interpreted as

postfix-expression . operator () ( expression-list${}_{opt}$ )