Re: String literal as template parameter?

On Apr 13, 6:23 pm, Daniel Krügler <daniel.krueg...@[EMAIL PROTECTED]
>
wrote:
> IMO the OP is aware that *current* C++ does not have
> variadic templates. But realizing that C++0x will
> be finished somewhere in 2009 his example is quite
> reasonable, because variadic templates do have *very*
> high chances to be introduced into C++0x.

"*very* high" is understating it. They are in the draft, and with a
working implementation already, there are chances of about nil +- zero
of getting removed for some reason.

> I find his extension proposal to allow a string-literal
> as an alternative argument of variadic non-type templates
> (of character type) quite interesting. This is IMO the
> first approach, where I would see any chance of acceptance
> on implementors side.
> Early proposals - which had no variadic templates available
> and usually reasoned about 'char const*' template parameters -
> lead to several problematic situations, which I do not
> see to exist for this proposal.

Yeah. This is a good idea. It doesn't take a lot of wording either:

Under [temp.arg.nontype], paragraph 1, add "a string literal" as
another element of the list. Replace paragraph 2 with "A string
literal shall only appear as the last template parameter (including
default parameters)." Add a new paragraph that says "A string literal
non-type template parameter is intepreted as a series of character
literals, each representing one character from the string (in order)
and becoming a separate template parameter, with a final '\0' as the
last parameter (so that the number of resultant character literals is
one greater than the number of characters in the string literal)." and
add some appropriate example. Probably didn't get the standardese
quite right, but the point is that it is quite a minor change.

This is a good idea. It's simple and maintains backwards-
compatibility. I don't know for sure, but I do not see this taking a
lot of extra work from implementors. It also makes writing code about
three times easier. I wholly endorse this proposal (not that my
endorsement probably means much).

Sean Hunt


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