Search results
Results from the WOW.Com Content Network
Often, consuming code registers a callback for a particular type of event. When that event occurs, the callback is called. Callbacks are often used to program the graphical user interface (GUI) of a program that runs in a windowing system. The application supplies a reference to a custom callback function for the windowing system to call.
In this example, the code generated for each of the classes A, B and C will include a dispatch table that can be used to call Access on an object of that type, via a reference that has the same type. Class C will have an additional dispatch table, used to call Access on an object of type C via a reference of type B.
In computer programming, an anonymous function (function literal, expression or block) is a function definition that is not bound to an identifier.Anonymous functions are often arguments being passed to higher-order functions or used for constructing the result of a higher-order function that needs to return a function. [1]
As of the 2011 revision, the C++ language also supports closures, which are a type of function object constructed automatically from a special language construct called lambda-expression. A C++ closure may capture its context either by storing copies of the accessed variables as members of the closure object or by reference.
Method overloading, on the other hand, refers to differentiating the code used to handle a message based on the parameters of the method. If one views the receiving object as the first parameter in any method then overriding is just a special case of overloading where the selection is based only on the first argument.
The Watcom C/C++ compiler also uses the #pragma aux [20] directive that allows the user to specify their own calling convention. As its manual states, "Very few users are likely to need this method, but if it is needed, it can be a lifesaver".
Compared to using in-line code, invoking a function imposes some computational overhead in the call mechanism. [citation needed] A function typically requires standard housekeeping code – both at the entry to, and exit from, the function (function prologue and epilogue – usually saving general purpose registers and return address as a minimum).
The C and C++ syntax given above is the canonical one used in all the textbooks - but it's difficult to read and explain. Even the above typedef examples use this syntax. However, every C and C++ compiler supports a more clear and concise mechanism to declare function pointers: use typedef, but don't store