Re: templated function help

From:
James Kanze <james.kanze@gmail.com>
Newsgroups:
comp.lang.c++
Date:
Wed, 4 Feb 2009 02:42:19 -0800 (PST)
Message-ID:
<56ddf930-efd8-49bd-808e-d047e51a82a1@g39g2000pri.googlegroups.com>
On Feb 4, 4:40 am, p...@lib.hu wrote:

Is isspace overloaded? How?

I tried this in Cameau Online:

#include <vector>
#include <algorithm>
#include <ctype.h>

void foo()
{
   std::vector<char> v(10);
   std::find_if(v.begin(), v.end(), isspace);
}

end it compiles clean. Also in MSVC2008. I even tried to
force it by adding
#include <locale>
using namespace std;

still compiles.


If you include <locale> and add "using namespace std", it's
guaranteed by the standard not to compile. And doesn't with g++
(but surprisingly does with Sun CC and VC++).

Without the "using namespace std", of course, you're guaranteed
not to see the functions in <locale>, regardless, so the
ambiguity is not present. You still get undefined behavior at
runtime, of course, but that's a different question.

(If you meant that as the overload, in the originally
mentioned case locale was definitely not included)


The standard explicitly allows C++ headers to include any other
header. It's fully legal for <vector> or <algorithm> to include
<locale>. (It would be fully legal for an implementation to
just have a single, precompiled header, with everything in it.)

[hmm, it would be so nice to have gcc online too... ]


Given its price, there doesn't seem to be any reason not to have
a local copy. (That's actually almost true for Comeau. The
difference is that because Comeau is licenced software, I don't
have a right to install it on machines where I work.)

--
James Kanze (GABI Software) email:james.kanze@gmail.com
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