How do I assign an alias to a function name in C++?
There are different approaches:
With C++11 with non-template non-overloaded functions you can simply use:
const auto& new_fn_name = old_fn_name;
If this function has multiple overloads you should use
static_cast
:const auto& new_fn_name = static_cast<OVERLOADED_FN_TYPE>(old_fn_name);
Example: there are two overloads of function
std::stoi
int stoi (const string&, size_t*, int); int stoi (const wstring&, size_t*, int);
If you want to make an alias to the first version you should use the following:
const auto& new_fn_name = static_cast<int(*)(const string&, size_t*, int)>(std::stoi);
Note: there is no way to make an alias to overloaded function such that all its overloaded versions work, so you should always specify which exact function overload you want.
With C++14 you can go even further with
constexpr
template variables. That allows you to alias templated functions:template<typename T> constexpr void old_function(/* args */); template<typename T> constexpr auto alias_to_old = old_function<T>;
Moreover, starting with C++11 you have a function called
std::mem_fn
that allows to alias member functions. See the following example:struct A { void f(int i) { std::cout << "Argument: " << i << '\n'; } }; A a; auto greet = std::mem_fn(&A::f); // alias to member function // prints "Argument: 5" greet(a, 5); // you should provide an object each time you use this alias // if you want to bind an object permanently use `std::bind` greet_a = std::bind(greet, a, std::placeholders::_1); greet_a(3); // equivalent to greet(a, 3) => a.f(3);
You can create a function pointer or a function reference:
void fn()
{
}
//...
void (*p)() = fn;//function pointer
void (&r)() = fn;//function reference
typedef int (*printf_alias)(const char*, ...);
printf_alias holler = std::printf;
Should do you fine.