Re: #pragma once in ISO standard yet?

From:
James Kanze <james.kanze@gmail.com>
Newsgroups:
comp.std.c++
Date:
Sun, 16 Dec 2007 09:23:46 CST
Message-ID:
<b3501e05-b1f9-4c41-9d94-5a0b72ec9c6f@t1g2000pra.googlegroups.com>
On Dec 16, 7:06 am, akfmn...@t-online.de (Andre Kaufmann) wrote:

Bo Persson wrote:

[...]


 >2) Doesn't help much does it? If the #pragma once makes the compiler
 >NOT include the file, I'm toast!

Simply don't use #pragma once for this project, meaning disable the
extension completely ? I think this case is somewhat constructed, if you
are using the same include guards you are toasted too.


In which case, you might as well not have it in the language,
since library code can't count on it being activated.

And since there are common naming conventions on some
platforms for include guards, you will have a high likelihood
of having the same include guards in 2 files ----> ;-)


The common naming conventions will normally introduce a large
degree of randomness. To the point where a collision is less
likely than the server being destroyed by a meteorite (which of
course will cause serious compilation problems too).

And if the #pragma once has skipped the inclusion, it's the OS
fault. ;-).


And what does that buy me?

As I wrote in another post, I could live with a combination of
include guards and #pragma once. A named #pragma once

#pragma once(_MY_HEADER_FILE)
#pragma once(_MY_OTHER_HEADER_FILE)

Would save me 2 lines of code ;-),


2 lines which you neither write, nor ever look at. Most source
code files start with a copyright message, which is a lot longer
than 2 lines. Similarly, my source files also end with
meta-information for the editors. And the editor positions me
after the copyright and the include guard when I open file.

IMHO, it's just not worth the bother.

and the compiler could distinguish header files, even if the
OS can't.

So I go to the corporate IT manager (vice president) and
tell him that the setup of our international WAN is
incorrect, because it doesn't


Please tell me that your compiler doesn't include files
directly over WAN and instead you are using a source code
control system, which synchronizes your local sources so that
your compiler uses only local files and doesn't have any
problems with checking if 2 files are identical ;-)


Why should I do something that dumb. The rule is simply: two
identical copies aren't. The version control system is a file
server, which serves up the version you're supposed to be using.
(I've used a lot of different version control systems, using
different models, but this one is an order of magnitude better
than the others for large projects.)

support the #pragma once feature of my C++ compiler.

Do you think he will order a reconfiguration? :-)


You should tell him that the current topology doesn't support the latest
(potential) compiler standard and the company will be soon out of
business if the topology isn't changed ;-9


More likely, every one will ignore the latest standard, like
they did with "export".:-)

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