[Boost-users] Re: [Foreach]TroubleiteratingoverBoost.MultiIndexcontainers

From: Arkadiy Vertleyb (vertleyb_at_[hidden])
Date: 2005-03-04 09:37:49

"Thorsten Ottosen" <nesotto_at_[hidden]> wrote
> "Arkadiy Vertleyb" <vertleyb_at_[hidden]> wrote
> | "Thorsten Ottosen" <nesotto_at_[hidden]> wrote
> | > "Arkadiy Vertleyb" <vertleyb_at_[hidden]> wrote in message
>
> | > I don't get this. Surely one of the functions would be a better match
than
> | > the others and hence called.
> |
> | How is
> |
> | namespace MyNamespace
> | {
> |    template<class T> end(const T&);
> | }
> |
> | is better match than
> |
> | namespace YourNamespace
> | {
> |    template<class T> end(const T&);
> | }
> | ?
> |
> | And now:
> |
> | MyNamespace::Foo<YourNamespace::Bar> obj;
> | end(obj); // ?????
>
> Why would any function but the primary template be taking
> a const T& param, that is, why don't your
> YourNamespace::end() refer to some class in YourNamespace?

Because one may have many unrelated templates that support the same concept.
Consider your range library.  What if one wants to write end() that is good
for any std container?

I am not saying that taking "const T&" is a good thing to do.  All that I am
saying -- it is legal C++.  And one should be OK doing this in their own
namespace.

The worst thing about this is that your library can clash with not a user
code, but with some other library that user has no control about...

Regards,
Arkadiy