Re: standard namespace

From:
James Kanze <james.kanze@gmail.com>
Newsgroups:
comp.lang.c++
Date:
Wed, 22 Apr 2009 01:57:59 -0700 (PDT)
Message-ID:
<246a1d7e-8b48-4f78-86c3-f87b4071c236@s20g2000yqh.googlegroups.com>
On Apr 21, 6:36 pm, blargg....@gishpuppy.com (blargg) wrote:

Alf P. Steinbach wrote:

* blargg:

Alf P. Steinbach wrote:

[...]

I'd agree if the above were the reasoning, but the <c*>
headers DO reliably put those names IN namespace std, so
that one can consistently refer to standard names with
std:: in one's own code.


Puzzling.

What advantage do you see in that?

   * It's an advantage for you to write std::printf instead
   of just printf?


It's an advantage to be ABLE to write std::whatever when
whatever is a name from the standard library, rather than
having to write std::whatever for some names, and whatever for
others.


I'm not sure I follow. In my projects, I'm using several
standard libraries: C++, Posix, Sybase... And I do have to keep
them straight; I can't write std::pthread_mutex_init, for
example. And the look and feel of the C library is closer to
Posix than it is to C++, so it actually seems more natural to
not use std::. How is time, in time.h, different from poll, in
poll.h? And what about popen, in stdio.h (but not necessarily
in <cstdio>---at least, I can't find a document anywhere that
guarantees it). Not to mention that two of the most used
facilities in the C library, assert and errno, are macros, and
will be without the std:: even if I use the <c*> headers.

In most header files, you don't want a using directive, so the
consistency is a benefit:


Consistency is an enormous benefit. None of the other C
libraries I use (Posix, etc.) put their names in std::, so why
should the standard C library?

    [...]

Only in a header file where you don't want a using directive;
in a source file, you'd rather drop std:: entirely:


I disagree. Within a function, you might use a using
declaration, to shorten the name, but otherwise: the name of the
standard input in C++ is std::cin, not cin, and that's the way
you normally write it.

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