Re: [Boost-users] Errors when playing with lambda (1.32.0, VC7.1)

From: Peter Dimov (pdimov_at_[hidden])
Date: 2004-11-30 11:26:13

John.Wismar_at_[hidden] wrote:
> If I change the declaration of for_all to take the container by const
> reference, I get errors [See Error 1 pasted in below]:
>
> using namespace boost::lambda;
>
> class Foo {
> public:
>    void print() {
>        std::cout << "Foo::print()\n";
>    }
> };
>
> template <class Container, class Function>
> Function for_all(Container const &cont, Function f) {
>    return std::for_each(cont.begin(), cont.end(), f);
> }

You are trying to invoke the non-const member function Foo::print on a const 
Foo.

> Example 2:
> It looks from the docs like I should be able to rewrite the bind
> expression above using operator ->*, like so:
>
>    for_all(vec, (&_1 ->* &Foo::print));
>
> And, in fact this compiles cleanly (regardless of whether the
> container is passed by value or by const reference).  Foo::print()
> never gets called, though.  What am I doing wrong or not
> understanding here?

You didn't call the function: (&_1->*&Foo::print)().