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From: "Johannes Schaub (litb)" <schaub-johannes@web.de>
Newsgroups: comp.std.c++
Subject: Re: Getting rid of "typename ...::type" for some cases?
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Date: Mon,  8 Feb 2010 22:27:41 CST
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Daniel Krügler wrote:

> On 1 Feb., 18:38, "Johannes Schaub (litb)" <schaub-johan...@web.de>
> wrote:
>> I wonder whether it would be possible to get rid of "typename
>> <tmp>::type" for the most common cases (enable_if (?))
>>
>> template<bool C, typename T = void>
>> using enable_if = typename enable_if<C, T>::type;
>>
>> Does that allow the following?
>>
>> template<typename T>
>> enable_if<is_pointer<T>::value> f();
>>
>> If it does, has it been considered to make it that way?
> 
> I don't think that you can reintroduce the name enable_if,
> but except for this the approach looks both feasible and
> nice to me. Regarding your second question: I don't
> think that it has been considered - nice idea.
> 

I think were it would be most useful is for std::identity. I find myself
using it alot, and allowing for shorter typing would be very nice. I'm
thinking of "alias" or something similar:

alias<char[1]> &f();
operator alias<void()>*();
template<typename T> T implicit_cast(alias<T> t) { return t; }
f(alias<unsigned char>());


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