std::bind and boost::bind traps.

See more:

C++

Boost

#include <functional>
#include <boost/bind.hpp>
class A
{
public:
	A(){}
	~A(){}
	template<typename _Handler>
	void call_handler(_Handler handler)
	{
		handler();
	}
};

class B
{
public:
	template<typename _Handler>
	void call_handler(_Handler handler)
	{

	}
	template<typename _Handler>
	void run(_Handler handler)
	{
		m_a.call_handler(boost::bind(&B::call_handler<_Handler>, this, handler));
		//only can use boost::bind here
	}
	A m_a;
};
class Test
{
public:
	void handler()
	{

	}
};

int main()
{
	B b;
	Test t;
	b.run(boost::bind(&Test::handler,&t));//only can use std::bind here
}

this is my little test code above.
I am confused that I only can use bind in the specific order...see note above
if I change std::bind to boost::bind ,then compiler failed,vice versa.
tested with:
gcc 4.9.2 for cygwin with option:
g++ -std=c++11 -fdiagnostics-color=always -fdiagnostics-show-location=every-line -I"/cygdrive/e/opensource libs/boost" main.cpp
msvc 12.0(visual studio 2013 with update4) with default option.


gcc diagnostic messages:
In file included from /cygdrive/e/opensource libs/boost/boost/bind.hpp:22:0,
from main.cpp:3:
/cygdrive/e/opensource libs/boost/boost/bind/bind.hpp: In instantiation of ‘void boost::_bi::list2<a1,>::operator()(boost::_bi::type<void>, F&, A&, int) [with F = boost::_mfi::mf1<void,>, boost::_bi::list1<boost::_bi::value xmlns:boost="#unknown"><test*> > > >; A = boost::_bi::list0; A1 = boost::_bi::value<b*>; A2 = boost::_bi::bind_t<void,>, boost::_bi::list1<boost::_bi::value><test*> > >]’:
/cygdrive/e/opensource libs/boost/boost/bind/bind.hpp:893:50: required from ‘boost::_bi::bind_t<r,>::result_type boost::_bi::bind_t<r,>::operator()() [with R = void; F = boost::_mfi::mf1<void,>, boost::_bi::list1<boost::_bi::value><test*> > > >; L = boost::_bi::list2<boost::_bi::value><b*>, boost::_bi::bind_t<void,>, boost::_bi::list1<boost::_bi::value><test*> > > >; boost::_bi::bind_t<r,>::result_type = void]’
main.cpp:12:11: required from ‘void A::call_handler(_Handler) [with _Handler = boost::_bi::bind_t<void,>, boost::_bi::list1<boost::_bi::value><test*> > > >, boost::_bi::list2<boost::_bi::value><b*>, boost::_bi::bind_t<void,>, boost::_bi::list1<boost::_bi::value><test*> > > > >]’
main.cpp:27:3: required from ‘void B::run(_Handler) [with _Handler = boost::_bi::bind_t<void,>, boost::_bi::list1<boost::_bi::value><test*> > >]’
main.cpp:44:38: required from here
/cygdrive/e/opensource libs/boost/boost/bind/bind.hpp:313:34: error: invalid use of void expression
unwrapper<f>::unwrap(f, 0)(a[base_type::a1_], a[base_type::a2_]);
^

msvc 12.0 diagnostic messages:
1>------ Build started: Project: scince_x32, Configuration: Debug Win32 ------
1> main.cpp
1>e:\opensource libs\boost\boost\bind\bind.hpp(313): error C2664: 'void boost::_mfi::mf1<void,b,_handler>::operator ()(T *,A1) const' : cannot convert argument 2 from 'void' to 'boost::_bi::bind_t<void,boost::_mfi::mf0><void,test>,boost::_bi::list1<boost::_bi::value><t>>>'
1> with
1> [
1> _Handler=boost::_bi::bind_t<void,boost::_mfi::mf0><void,test>,boost::_bi::list1<boost::_bi::value><test>>>
1> , T=B
1> , A1=boost::_bi::bind_t<void,boost::_mfi::mf0><void,test>,boost::_bi::list1<boost::_bi::value><test>>>
1> ]
1> and
1> [
1> T=Test *
1> ]
1> Expressions of type void cannot be converted to other types
1> e:\opensource libs\boost\boost\bind\bind.hpp(893) : see reference to function template instantiation 'void boost::_bi::list2<boost::_bi::value><t>,boost::_bi::bind_t<void,boost::_mfi::mf0><void,test>,boost::_bi::list1<boost::_bi::value><test>>>>::operator ()<f,boost::_bi::list0>(boost::_bi::type<void>,F &,A &,int)' being compiled
1> with
1> [
1> T=B *
1> , F=boost::_mfi::mf1<void,b,boost::_bi::bind_t><void,boost::_mfi::mf0><void,test>,boost::_bi::list1<boost::_bi::value><test>>>>
1> , A=boost::_bi::list0
1> ]
1> e:\opensource libs\boost\boost\bind\bind.hpp(893) : see reference to function template instantiation 'void boost::_bi::list2<boost::_bi::value><t>,boost::_bi::bind_t<void,boost::_mfi::mf0><void,test>,boost::_bi::list1<boost::_bi::value><test>>>>::operator ()<f,boost::_bi::list0>(boost::_bi::type<void>,F &,A &,int)' being compiled
1> with
1> [
1> T=B *
1> , F=boost::_mfi::mf1<void,b,boost::_bi::bind_t><void,boost::_mfi::mf0><void,test>,boost::_bi::list1<boost::_bi::value><test>>>>
1> , A=boost::_bi::list0
1> ]
1> e:\opensource libs\boost\boost\bind\bind.hpp(891) : while compiling class template member function 'void boost::_bi::bind_t<void,boost::_mfi::mf1><void,b,_handler>,boost::_bi::list2<boost::_bi::value><t>,boost::_bi::bind_t<void,boost::_mfi::mf0><void,test>,boost::_bi::list1<boost::_bi::value><test>>>>>::operator ()(void)'
1> with
1> [
1> _Handler=boost::_bi::bind_t<void,boost::_mfi::mf0><void,test>,boost::_bi::list1<boost::_bi::value><test>>>
1> , T=B *
1> ]
1> e:\c++program\scince_x32\scince_x32\main.cpp(12) : see reference to function template instantiation 'void boost::_bi::bind_t<void,boost::_mfi::mf1><void,b,_handler>,boost::_bi::list2<boost::_bi::value><t>,boost::_bi::bind_t<void,boost::_mfi::mf0><void,test>,boost::_bi::list1<boost::_bi::value><test>>>>>::operator ()(void)' being compiled
1> with
1> [
1> _Handler=boost::_bi::bind_t<void,boost::_mfi::mf0><void,test>,boost::_bi::list1<boost::_bi::value><test>>>
1> , T=B *
1> ]
1> e:\c++program\scince_x32\scince_x32\main.cpp(27) : see reference to class template instantiation 'boost::_bi::bind_t<void,boost::_mfi::mf1><void,b,_handler>,boost::_bi::list2<boost::_bi::value><t>,boost::_bi::bind_t<void,boost::_mfi::mf0><void,test>,boost::_bi::list1<boost::_bi::value><test>>>>>' being compiled
1> with
1> [
1> _Handler=boost::_bi::bind_t<void,boost::_mfi::mf0><void,test>,boost::_bi::list1<boost::_bi::value><test>>>
1> , T=B *
1> ]
1> e:\c++program\scince_x32\scince_x32\main.cpp(44) : see reference to function template instantiation 'void B::run<boost::_bi::bind_t><void,boost::_mfi::mf0><void,test>,boost::_bi::list1<boost::_bi::value><t>>>>(_Handler)' being compiled
1> with
1> [
1> T=Test *
1> , _Handler=boost::_bi::bind_t<void,boost::_mfi::mf0><void,test>,boost::_bi::list1<boost::_bi::value><test>>>
1> ]
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========