c++ 中的静态虚函数

发布于 2024-11-14 09:23:59 字数 75 浏览 4 评论 0原文

我有一个基类和一个派生类，我想更改基函数，同时保持它们静态，因为它们应该作为静态传递给其他函数。

我怎样才能做到这一点？

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柒夜笙歌凉 2024-11-21 09:23:59

ATL 框架通过将基类设为模板，然后让派生类将其类类型作为模板参数传递，从而绕过了无虚拟静态的限制。然后，基类可以在需要时调用派生类静态，例如：

template< class DerivedType >
class Base
{
public:
  static void DoSomething() { DerivedType::DoSomethingElse(); }
};

class Derived1 : public Base<Derived1>
{
public:
  static void DoSomethingElse() { ... }
};

class Derived2 : public Base<Derived2>
{
public:
  static void DoSomethingElse() { ... }
};

这被称为奇怪的重复模板模式，它可以是用于实现静态多态性。

The ATL framework gets around the limitation of no virtual statics by making the base class be a template, and then having derived classes pass their class type as a template parameter. The base class can then call derived class statics when needed, eg:

template< class DerivedType >
class Base
{
public:
  static void DoSomething() { DerivedType::DoSomethingElse(); }
};

class Derived1 : public Base<Derived1>
{
public:
  static void DoSomethingElse() { ... }
};

class Derived2 : public Base<Derived2>
{
public:
  static void DoSomethingElse() { ... }
};

This is known as Curiously recurring template pattern, which can be used to implement static polymorphism.

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最丧也最甜 2024-11-21 09:23:59

您的意思是您需要一个指向静态函数的指针（例如，作为参数传递给另一个需要指向静态函数的指针的函数），但您需要虚拟地访问该函数指针？在这种情况下，使用虚函数来获取函数指针：

typedef void (*function)();
void do_stuff_with_function(function);

struct Base {
    virtual ~Base() {}
    virtual function get_function() = 0;
};

struct Derived : Base {
    function get_function() {return my_function;}
    static void my_function();
};

Derived d;
do_stuff_with_function(d.get_function());

Do you mean you need a pointer to a static function (e.g. to pass as an argument to another function that requires a pointer to a static function), but you need to access that function pointer virtually? In that case, use a virtual function to get the function pointer:

typedef void (*function)();
void do_stuff_with_function(function);

struct Base {
    virtual ~Base() {}
    virtual function get_function() = 0;
};

struct Derived : Base {
    function get_function() {return my_function;}
    static void my_function();
};

Derived d;
do_stuff_with_function(d.get_function());

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