我有一个C++类,我试图使用std :: bind1st将成员函数绑定到'this'参数.例如:
class MyClass
{
public:
void Foo()
{
using namespace std;
// this works fine
this->Bar();
// this also works fine
mem_fun( &MyClass::Bar )( this );
// this does not
bind1st( mem_fun( &MyClass::Bar ), this )();
// this is not a possibility for this program
boost::bind( &MyClass::Bar, this )();
};
void Bar()
{
};
};
当我添加最后一个'bind1st'行时,我得到以下编译器错误:
1>stl/_function.h(189) : error C2039: 'second_argument_type' : is not a member of 'stlp_std::mem_fun_t<_Ret,_Tp>'
1> with
1> [
1> _Ret=void,
1> _Tp=MyClass
1> ]
1> .\MyClass.cpp(50) : see reference to class template instantiation 'stlp_std::binder1st<_Operation>' being compiled
1> with
1> [
1> _Operation=stlp_std::mem_fun_t<void,MyClass>
1> ]
1>stl/_function.h(189) : error C2146: syntax error : missing ',' before identifier 'second_argument_type'
1>stl/_function.h(189) : error C2065: 'second_argument_type' : undeclared identifier
1>stl/_function.h(190) : error C2955: 'stlp_std::unary_function' : use of class template requires template argument list
1> stl/_function_base.h(40) : see declaration of 'stlp_std::unary_function'
1>stl/_function.h(191) : error C2039: 'second_argument_type' : is not a member of 'stlp_std::mem_fun_t<_Ret,_Tp>'
1> with
1> [
1> _Ret=void,
1> _Tp=MyClass
1> ]
1>stl/_function.h(191) : error C2146: syntax error : missing ',' before identifier 'second_argument_type'
1>stl/_function.h(191) : error C2065: 'second_argument_type' : undeclared identifier
1>stl/_function.h(194) : error C2955: 'stlp_std::unary_function' : use of class template requires template argument list
1> stl/_function_base.h(40) : see declaration of 'stlp_std::unary_function'
1>stl/_function.h(195) : error C2955: 'stlp_std::unary_function' : use of class template requires template argument list
1> stl/_function_base.h(40) : see declaration of 'stlp_std::unary_function'
1>stl/_function.h(197) : error C2146: syntax error : missing ';' before identifier '_ArgParamType'
1>stl/_function.h(197) : error C3254: 'stlp_std::binder1st<_Operation>' : class contains explicit override 'param_type' but does not derive from an interface that contains the function declaration
1> with
1> [
1> _Operation=stlp_std::mem_fun_t<void,MyClass>
1> ]
1>stl/_function.h(197) : error C2838: 'param_type' : illegal qualified name in member declaration
1>stl/_function.h(197) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
1>stl/_function.h(197) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
1>stl/_function.h(198) : error C2146: syntax error : missing ';' before identifier '_ConstArgParamType'
1>stl/_function.h(198) : error C3254: 'stlp_std::binder1st<_Operation>' : class contains explicit override 'const_param_type' but does not derive from an interface that contains the function declaration
1> with
1> [
1> _Operation=stlp_std::mem_fun_t<void,MyClass>
1> ]
1>stl/_function.h(198) : error C2838: 'const_param_type' : illegal qualified name in member declaration
1>stl/_function.h(198) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
1>stl/_function.h(198) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
1>stl/_function.h(199) : error C2039: 'first_argument_type' : is not a member of 'stlp_std::mem_fun_t<_Ret,_Tp>'
1> with
1> [
1> _Ret=void,
1> _Tp=MyClass
1> ]
1>stl/_function.h(199) : error C2146: syntax error : missing ',' before identifier 'first_argument_type'
1>stl/_function.h(199) : error C2065: 'first_argument_type' : undeclared identifier
1>stl/_function.h(199) : error C2955: 'stlp_std::__call_traits' : use of class template requires template argument list
1> stl/type_traits.h(452) : see declaration of 'stlp_std::__call_traits'
1>stl/_function.h(203) : error C2039: 'first_argument_type' : is not a member of 'stlp_std::mem_fun_t<_Ret,_Tp>'
1> with
1> [
1> _Ret=void,
1> _Tp=MyClass
1> ]
1>stl/_function.h(203) : error C2146: syntax error : missing ';' before identifier '_M_value'
1>stl/_function.h(203) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
1>stl/_function.h(203) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
1>stl/_function.h(208) : error C2061: syntax error : identifier '_ConstArgParamType'
1>stl/_function.h(211) : error C2061: syntax error : identifier '_ArgParamType'
1>stl/_function.h(212) : error C2535: '_Result stlp_std::binder1st<_Operation>::operator ()(void) const' : member function already defined or declared
1> with
1> [
1> _Operation=stlp_std::mem_fun_t<void,MyClass>
1> ]
1> stl/_function.h(208) : see declaration of 'stlp_std::binder1st<_Operation>::operator ()'
1> with
1> [
1> _Operation=stlp_std::mem_fun_t<void,MyClass>
1> ]
我正在使用STLPort v5.2.1进行标准库实现.
通常,我会切换到boost :: bind并使用它.不幸的是,这不适用于此应用程序.
我该怎么做才能获得我正在寻找的功能？
谢谢,PaulH
编辑:为了更清楚,我正在寻找一种方法来使一元函数适应你所谓的不带参数的函数.我想"绑定" this到MyClass::Bar.
class SomeOtherClass
{
public:
template< typename Fcn >
void ExecuteFcn( Fcn fcn )
{
fcn();
};
};
some_other_class.ExecuteFcn( bind1st( mem_fun( &MyClass::Bar ), this );
你想用bind1st完成什么？
该bind1st函数采用二进制函数,并通过隐含第一个参数使其适应一元函数(这可能不是最好的描述,对不起).返回值mem_fun是一元函数.
该mem_fun函数返回成员函数的适配器.改编后的函数不带任何参数,但返回的适配器接受一个参数,一个指向要使用的MyClass对象的指针.
所以,基本上,你的mem_fun调用是返回一个接受一个参数bind1st的适配器,但是期望一个带有两个参数的适配器.有一个mem_fun1返回一个带有两个参数的适配器,第一个是对象指针,第二个是函数的参数,但这不是你想要的.
事实上,我不太明白你想要做什么; 为什么普通mem_fun版不适合？如果您需要将对象指针"附加"到适配器,我认为您不能使用当前标准库执行此操作,除非您使用bind.
当然,您可以创建一个包含对象指针的包装类,然后只需定义operator()以使用该对象调用适配器.
// Quick and dirty example of this.
// You could extend this with a second template parameter for return type, if
// needed. Just be sure to specialize for void if you do that.
template<typename Object>
struct bound_mem_fun_t {
bound_mem_fun_t(mem_fun_t<void, Object> f, Object* o) : fun(f), obj(o) { }
void operator()() { fun(obj); }
mem_fun_t<void, Object> fun;
Object* obj;
};
MyClass a;
bound_mem_fun_t<MyClass> func(mem_fun(&MyClass::Bar), &a);
func();