如何在 C++ 中为函数名分配别名? [英] How do I assign an alias to a function name in C++?

问题描述

为类型、变量或命名空间创建新名称很容易.但是如何为函数分配一个新名称呢?例如，我想对 printf 使用名称 holler.#define 很明显...还有其他方式吗?

It's easy to create a new name for a type, a variable or a namespace. But how do I assign a new name to a function? For example, I want to use the name holler for printf. #define is obvious... any other way?

解决方案:

1. #define holler printf
2. void (*p)() = fn;//函数指针
3. void (&r)() = fn;//函数参考
4. inline void g(){ f();}

推荐答案

有不同的方法:

• 使用带有非模板非重载函数的 C++11，您可以简单地使用:

• With C++11 with non-template non-overloaded functions you can simply use:

const auto& new_fn_name = old_fn_name;

如果这个函数有多个重载，你应该使用static_cast:

const auto& new_fn_name = static_cast<OVERLOADED_FN_TYPE>(old_fn_name);

示例:函数 std::stoi

int stoi (const string&, size_t*, int);
int stoi (const wstring&, size_t*, int);

如果你想为第一个版本做一个别名，你应该使用以下内容:

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);

注意:无法为重载函数创建别名，使其所有重载版本都能正常工作，因此您应该始终指定所需的确切函数重载.

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.

使用 C++14，您可以使用 constexpr 模板变量走得更远.这允许您为模板化函数设置别名:

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>;

此外，从 C++11 开始，您有一个名为 std::mem_fn 的函数，它允许为成员函数设置别名.请参见以下示例:

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 << '
';
   }
};


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);

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