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Re: Could we use T:X to abbreviate "typename T::X"? (and get cleaner code)

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Am 27.02.2013 18:05, schrieb SG:
>
> On Jan 23, 12:26 am, Daniel Krügler wrote:
> [snip]
>
>>   template<bool C, class T = void>
>>   using EnableIf = typename std::enable_if<C, T>::type;
>
>
> Is the right hand side of this template alias considered an immediate
> context with respect to SFINAE?


Let me start with a general remark in regard to "immediate context"
used in 14.8: The Standard committee had introduced this term knowing
that this is a fuzzy definition. In regard to alias templates the
wording *could* be interpreted as if the "definition of alias would be
a different context. In general, this is not intended, because alias
substitution is supposed to happen very early. I think that this usage
of alias template is safe (and considered to be in the immediate
context) when you compare it with

http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#1558

The current suggestion is that

a) Substitution happens in the immediate context of the template that
had causes the substitution

b) Access checking (see CWG issue

http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#1554
) is performed in the context of the definition of alias template.

HTH & Greetings from Bremen,

Daniel Krügler



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Could we use T:X to abbreviate "typename T::X"? (and get cleaner code) Walter Mascarenhas<walter.mascarenhas@googlemail.com> - 2013-01-22 10:54 -0600
  Re: Could we use T:X to abbreviate "typename T::X"? (and get cleaner code) Daniel Krügler <daniel.kruegler@googlemail.com> - 2013-01-22 15:26 -0800
    Re: Could we use T:X to abbreviate "typename T::X"? (and get cleaner code) Walter Mascarenhas<walter.mascarenhas@googlemail.com> - 2013-01-24 15:15 -0800
    Re: Could we use T:X to abbreviate "typename T::X"? (and get cleaner code) SG<s.gesemann@googlemail.com> - 2013-02-27 09:05 -0800
      Re: Could we use T:X to abbreviate "typename T::X"? (and get cleaner code) Daniel Krügler <daniel.kruegler@googlemail.com> - 2013-02-27 10:52 -0800

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