Topic: Rationale behind "class" in a template declaration?
Author: "Carl Daniel" <cpdaniel@pacbell.net>
Date: Thu, 7 Feb 2002 21:06:20 GMT Raw View
"disgruntled goat" <the_disgruntled_goat@hotmail.com> wrote in message
news:818a6a96.0202062308.407f410b@posting.google.com...
> Why is the keyword 'class' used here?
>
> template<class T> void func(T);
> ^^^^^
Two words: Backwards compatibility.
This usage was common long before the 'typename' keyword was added to the
language.
-cd
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Author: Ron Natalie <ron@sensor.com>
Date: Fri, 8 Feb 2002 01:11:07 GMT Raw View
disgruntled goat wrote:
>
> Why is the keyword 'class' used here?
>
> template<class T> void func(T);
> ^^^^^
>
> Why did the standards committee not just state that 'typename' must be
> used?
Because C++ was using class for that purpose long before anybody came up with
the typename keyword.
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Author: comeau@panix.com (Greg Comeau)
Date: Fri, 8 Feb 2002 01:11:21 GMT Raw View
In article <818a6a96.0202062308.407f410b@posting.google.com>,
disgruntled goat <the_disgruntled_goat@hotmail.com> wrote:
>Why is the keyword 'class' used here?
>
>template<class T> void func(T);
> ^^^^^
>
>Why did the standards committee not just state that 'typename' must be
>used? Is there a good reason to allow 'class' in a template
>declaration when one can already use typename? It in no way mandates
>the parameters be of class type, and is thus causes a needless bit of
>confusion.
>
>Basically I'm just confused. The keyword 'typename' would seem to be
>perfect for this situation. Why allow 'class' as well? The only
>possible reason I can think of is if 'typename' was not added to the
>standard until *after* templates had been originated.
And that's what happened (it was added to the draft a bit after
templates were in implementations already).
Some people actually like class there (personally I don't) too.
--
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Author: the_disgruntled_goat@hotmail.com (disgruntled goat)
Date: Thu, 7 Feb 2002 18:21:05 GMT Raw View
Why is the keyword 'class' used here?
template<class T> void func(T);
^^^^^
Why did the standards committee not just state that 'typename' must be
used? Is there a good reason to allow 'class' in a template
declaration when one can already use typename? It in no way mandates
the parameters be of class type, and is thus causes a needless bit of
confusion.
Basically I'm just confused. The keyword 'typename' would seem to be
perfect for this situation. Why allow 'class' as well? The only
possible reason I can think of is if 'typename' was not added to the
standard until *after* templates had been originated.
If anyone can straighten this out for me, please do. Thanks.
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