Re: [boost] Disable_if_type / is_pair

Subject: Re: [boost] Disable_if_type / is_pair
From: Stewart, Robert (Robert.Stewart_at_[hidden])
Date: 2011-10-11 14:40:03

Olaf van der Spek wrote:
>
[reordering to compress]

> template <class T, class U>
> typename T::value_type::second_type* find_ptr(T& c, U v);
>
> template <class T, class U>
> typename iterator_traits<typename T::iterator>::pointer
> find_ptr(T& c, U v);
>
> What is the recommended way to disable the second overload? I
> didn't find a is_pair type_trait or disable_if_type.

pair doesn't have a nested type "iterator", so SFINAE would disable the second.

> I call the find() member, which for example vector doesn't
> have. How should I use the free find() if a member find() isn't
> available?

The TypeTraits extension doesn't have a has_member trait, but probably uses some techniques that could be employed to detect T::find.  The Type Traits Introspection library provides BOOST_TTI_HAS_MEMBER_FUNCTION which, based upon the name, would apply.

_____
Rob Stewart                           robert.stewart_at_[hidden]
Software Engineer                     using std::disclaimer;
Dev Tools & Components
Susquehanna International Group, LLP  http://www.sig.com

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