weak bind的std实现

灰太狼 2022-06-13 02:48 160阅读 0赞

转载请注明出处：[http://blog.csdn.net/wangji163163/article/details/73698662][http_blog.csdn.net_wangji163163_article_details_73698662]

弱bind实现，防止function是成员的时候，bind shared\_from\_this 形成自引用，导致内存泄露。

#include <stdio.h>
    #include <memory>
    #include <functional>
    namespace stdx = std;
    template<typename _Class, typename... _Args>
    class Weak_Binder0
    {
    	typedef stdx::weak_ptr<_Class>				WP;
    	typedef stdx::shared_ptr<_Class>			SP;
    	typedef stdx::function<void(_Class*,_Args...)>FN;
    public:
    	Weak_Binder0(const WP& wp, const FN& f) :wp_(wp), f_(f) {}
    	void operator()(_Args&&... args) const { if (SP sp = wp_.lock())f_(sp.get(), stdx::forward<_Args>(args)...); }
    private:
    	WP wp_;
    	FN f_;
    };
    template<typename _Ret, typename _Class, typename... _Args>
    class Weak_Binder
    {
    	typedef _Ret								RT;
    	typedef stdx::weak_ptr<_Class>				WP;
    	typedef stdx::shared_ptr<_Class>			SP;
    	typedef stdx::function<RT(_Class*, _Args...)>FN;
    public:
    	Weak_Binder(const RT& fail, const WP& wp, const FN& f) :fail_(fail), wp_(wp), f_(f) {}
    	_Ret operator()(_Args&&... args) const
    	{
    		if (SP sp = wp_.lock())return f_(sp.get(), stdx::forward<_Args>(args)...);
    		return fail_;
    	}
    private:
    	RT fail_;
    	WP	wp_;
    	FN f_;
    };
    template<typename _Class, typename... _Args>
    Weak_Binder0<_Class, _Args...> wbind(const stdx::shared_ptr<_Class>& sp, void (_Class::*f)(_Args...))
    {
    	return Weak_Binder0<_Class, _Args...>(sp, f);
    }
    template<typename _Class, typename... _Args>
    Weak_Binder0<_Class, _Args...> wbind(const stdx::shared_ptr<_Class>& sp, void (_Class::*f)(_Args...) const)
    {
    	return Weak_Binder0<_Class, _Args...>(sp, f);
    }
    template<typename _Ret, typename _Class, typename... _Args>
    Weak_Binder<_Ret, _Class, _Args...> wbind(const _Ret&& fail, const stdx::shared_ptr<_Class>& sp, _Ret(_Class::*f)(_Args...))
    {
    	return Weak_Binder<_Ret, _Class, _Args...>(fail, sp, f);
    }
    template<typename _Ret, typename _Class, typename... _Args>
    Weak_Binder<_Ret, _Class, _Args...> wbind(const _Ret&& fail, const stdx::shared_ptr<_Class>& sp, _Ret(_Class::*f)(_Args...) const)
    {
    	return Weak_Binder<_Ret, _Class, _Args...>(fail, sp, f);
    }
    //
    template<typename _Class, typename... _Args>
    Weak_Binder0<_Class, _Args...> wbind(const stdx::weak_ptr<_Class>& sp, void (_Class::*f)(_Args...))
    {
    	return Weak_Binder0<_Class, _Args...>(sp, f);
    }
    template<typename _Class, typename... _Args>
    Weak_Binder0<_Class, _Args...> wbind(const stdx::weak_ptr<_Class>& sp, void (_Class::*f)(_Args...) const)
    {
    	return Weak_Binder0<_Class, _Args...>(sp, f);
    }
    template<typename _Ret, typename _Class, typename... _Args>
    Weak_Binder<_Ret, _Class, _Args...> wbind(const _Ret& fail, const stdx::weak_ptr<_Class>& sp, _Ret(_Class::*f)(_Args...))
    {
    	return Weak_Binder<_Ret, _Class, _Args...>(fail, sp, f);
    }
    template<typename _Ret, typename _Class, typename... _Args>
    Weak_Binder<_Ret, _Class, _Args...> wbind(const _Ret& fail, const stdx::weak_ptr<_Class>& sp, _Ret(_Class::*f)(_Args...) const)
    {
    	return Weak_Binder<_Ret, _Class, _Args...>(fail, sp, f);
    }
    class  Test
    {
    	int m;
    public:
    	Test(int k):m(k)
    	{
    	}
    	int print1(int i)
    	{
    		printf("[%d]print1:%d\n",m,i);
    		return i;
    	}
    	void print0()
    	{
    		printf("[%d]print0\n",m);
    	}
    };
    int main(int argc, char** argv)
    {
    	stdx::shared_ptr<Test> sp(new Test(1000));
    	int r(0);
    	stdx::function<void(void)> f0 = ::wbind(sp, &Test::print0);
    	stdx::function<int(int)>   f1 = ::wbind(-1,sp, &Test::print1);
    	f0();
    	r = f1(100);printf("r=%d\n", r);
    	sp.reset();
    	f0();
    	r = f1(100);printf("r=%d\n", r);
    	return 0;
    }

输出

$./test_sig 
    [1000]print0
    [1000]print1:100
    r=100
    r=-1

实现了std版本，boost版本还未实现，原因是boost的forward与C++11的寓意不一样。

[http_blog.csdn.net_wangji163163_article_details_73698662]: http://blog.csdn.net/wangji163163/article/details/73698662