Re: Is there a typedef or a using-declaration equivalent for templates ?

From:
=?ISO-8859-1?Q?Daniel_Kr=FCgler?= <daniel.kruegler@googlemail.com>
Newsgroups:
comp.lang.c++.moderated
Date:
Tue, 20 Mar 2012 16:17:05 -0700 (PDT)
Message-ID:
<jk9hhk$2vm$1@dont-email.me>
On 2012-03-20 09:28, Timothy Madden wrote:

On 20.03.2012 07:03, Daniel Kr?gler wrote:

From your first description I guess you mean something like


template<class>
struct A {
template<class...>
struct I {};
};

as dependent base class template and usage within B like this:

template<class T>
struct B : A<T> {
typedef A<T> super_t;
typename super_t::template I<T, int> m;
};

Is this correct?


Yes, except I just want
super_t::template I
and not
super_t::template I<T, int>
because I want to later specialize I with many different arguments.


Now I'm completely confused given your original description where you wrote:

"I end up with a rather long construct to use throughout my
class:
    base_class_name:: template templ_name <arg,...>"

Can you please provide a simple and self-explaining example?

Well I do not have gcc 4.7 yet (but 4.6.1 from MinGW), but I still have
a question:

Even with an alias-declaration, how does the compiler know if the named
template is a function template or a class template ? Or is the
alias-declaration only used for class templates ?


This has nothing to to with class templates, but with types instead. An
alias declaration always declares a type or a family of types (when a
template). How could this be related to function templates, which are
families of functions?

template <class... Args>
using I = super_t::template I<Args...>;

Recall that super_t is dependent, so
super_t::template I
means just about nothing to the compiler...


Sure, it means that template I must refer to a type (family), anything
else could only be ill-formed. Should I have misunderstood what you are
trying to say, please elaborate in more detail.

HTH & Greetings from Bremen,

Daniel Kr?gler

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