Re: [Boost-users] [bind] VC++ 2008 compiler error

From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2008-03-13 20:05:02

AMDG

Boris wrote:
> Can anyone explain to me why VC++ 2008 refuses to compile this code:
>
> void empty() { }
>
> template <class T>
> void foo(T t)
> {
> 	// error C2664: 'void (T)' : cannot convert
> 	// parameter 1 from 'void' to 'boost::_bi::bind_t<R,F,L>'
> 	boost::bind(bar<T>, t)();
>
> 	// This one works though:
> 	boost::bind(bar<T>, _1)(t);
> }
>
> template <class T>
> void bar(T t)
> {
> 	t();
> }
>
> int main()
> {
> 	foo(boost::bind(empty));
> }
>
> Is this a problem with the VC++ 2008 compiler or am I trying to do  
> something which isn't supported by Boost.Bind?
>   
The expression which you are creating in multiple stages is

boost::bind(bar<T>, boost::bind(empty))()

Bind tries to evaluates this as bar<T>(empty())
rather than what you intended: bar<T>(empty)

Try:

foo(boost::protect(boost::bind(empty)));

To prevent composition.

In Christ,
Steven Watanabe