"Old Wolf" <oldwolf@inspire.net.nz> wrote in message
news:843a4f78.0408151512.4420cea8@posting.google.c om...[color=blue]
> I have a member function that acts on an object. I would also like to
> have a member function that acts on a container of such objects,
> using std::for_each. I tried:
>
> #include <algorithm>
> #include <functional>
>
> struct bar {
> template<typename T> void foo(T const &);
> template<typename InIt> void foo(InIt begin, InIt end)
> { std::for_each(begin, end, foo); }
> };
>
> but got a compiler error (at the point of calling foo, not at the point
> of declaration) because 'foo' was a pointer to member function, rather
> than a pointer to function. So I tried:
> std::for_each(begin, end, std::mem_fun(&foo));
> but got the error:
> Could not find a match for std::mem_fun<S,T>(void (bar::*)(const T &))
>
> Finally I tried:
> std::for_each(begin, end, std::mem_fun(&foo<typename[/color]
InIt::value_type>));[color=blue]
> but got an ICE.
>
> What is the correct usage?
>
> I have in fact solved the problem with:
> { for (; begin != end; ++begin) fo(*begin); }
> but would like to know if it is possible with for_each anyway.[/color]
This looks like a case where attempting to only use the functionality
provided by the standard library is difficult, if not impossible. You first
create an instance of mem_fun1_t<void, bar, const T&>. You need to bind the
first argument of the mem_fun1_t's operator() to this, so you need to create
a binder1st, which will expose an operator() which will declare a const T&&,
which is not allowed. The boost library may make this easier. However, I
wouldn't worry about it, because the for loop is much clearer.
--
David Hilsee
