Explaining the Versatile Concept of Delegates in C

A delegate in C is a programming construct that allows you to pass a function pointer as an argument. This enables you to create callbacks that can be invoked asynchronously or in different contexts.

There are various approaches to implementing delegates in C , including:

Functors

Functors are objects that define an operator() function, effectively making them callable.

struct Functor {
    int operator()(double d) {
        return (int)d   1;
    }
};

Lambda Expressions (C 11 onwards)

Lambda expressions provide a concise syntax for creating delegates inline:

auto func = [](int i) -> double { return 2 * i / 1.15; };

Function Pointers

Direct function pointers can be used to represent delegates:

int f(double d) { ... }
typedef int (*MyFuncT)(double d);

Pointer to Member Functions

Pointers to member functions provide a fast way to create delegates for class members:

struct DelegateList {
    int f1(double d) { }
    int f2(double d) { }
};
typedef int (DelegateList::* DelegateType)(double d);

std::function

std::function is a standard C template that can store any callable, including lambdas, functors, and function pointers.

#include 
std::function f = [any of the above];

Binding (Using std::bind)

Binding allows you to partially apply arguments to a delegate, making it convenient for calling member functions:

struct MyClass {
    int DoStuff(double d); // actually (MyClass* this, double d)
};
std::function f = std::bind(&MyClass::DoStuff, this, std::placeholders::_1);

Templates

Templates can accept any callable that matches the argument list:

template 
int DoSomething(FunctionT func) {
    return func(3.14);
}

Delegates are a versatile tool in C that enable you to enhance your code's flexibility and maintainability. By choosing the appropriate delegate approach for your specific needs, you can effectively pass functions as parameters, handle callbacks, and implement asynchronous programming in C .