Search results
Results from the WOW.Com Content Network
In computer programming, a function object [a] is a construct allowing an object to be invoked or called as if it were an ordinary function, usually with the same syntax (a function parameter that can also be a function). In some languages, particularly C++, function objects are often called functors (not related to the functional programming ...
C++ also allows objects to provide an implementation of the function call operation. The Standard Template Library accepts these objects (called functors) as parameters. Many dynamic languages, such as JavaScript, Lua, Python, Perl [1] [2] and PHP, allow a function object to be passed.
pointer to function;; pointer to member function;; functor;; lambda expression.; std::function is a template class that can hold any callable object that matches its signature.; In C++, any class that overloads the function call operator operator() may be called using function-call syntax.
A functor is an object of a class type that implements the function-call operator, allowing the object to be used within expressions using the same syntax as a function call. Functors are more powerful than simple function pointers, being able to contain their own data values, and allowing the programmer to emulate closures .
The C++ Standard Library includes in the header file functional many different predefined function objects, including arithmetic operations (plus, minus, multiplies, divides, modulus, and negate), comparisons (equal_to, not_equal_to, greater, less, greater_equal, and less_equal), and logical operations (logical_and, logical_or, and logical_not).
takes one or more functions as arguments (i.e. a procedural parameter, which is a parameter of a procedure that is itself a procedure), returns a function or value as its result. All other functions are first-order functions. In mathematics higher-order functions are also termed operators or functionals.
Manipulation of these parameters can be done by using the routines in the standard library header < stdarg. h >. In C++, the return type can also follow the parameter list, which is referred to as a trailing return type. The difference is only syntactic; in either case, the resulting signature is identical:
PHP has hundreds of base functions and thousands more from extensions. Prior to PHP version 5.3.0, functions are not first-class functions and can only be referenced by their name, whereas PHP 5.3.0 introduces closures. [35] User-defined functions can be created at any time and without being prototyped. [35]