Re: [Boost-users] Nullary metafunction

Steven Watanabe writes:

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er writes:

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Hi All,

I'm looking for template<typename> class F such that

F<T>::type is T::type if it exists, T itself otherwise. [...] Something like this could do: [...] Wouldn't it be easier to use the MPL components

AMDG Joaquin M Lopez Munoz wrote: that already exist?

BOOST_MPL_HAS_XXX_TRAIT_DEF(type);

template<class T> struct nested_type : boost::mpl::eval_if {};

Oh, yes, that's definitely the way to go, didn't remember about BOOST_MPL_HAS_XXX_TRAIT_DEF. Sorry for the noise. Joaquín M López Muñoz Telefónica, Investigación y Desarrollo