RE: [Cppunit-devel] Duplicated #includes

[Summerwill, B. <BSu...@eu...>]

They don't cause any trouble as such, but they will increase
compile times, maybe substantially.

On most compilers, the preprocessor will have to fully expand the
second #include (including traversing the indirect includes which
the header itself has *), before it can notice the #ifndef, and
discard the lot.

MSVC++ solves this with #pragma once, but this isn't a portable
solution.  I just wanted to point these duplications out, as
summed over the whole application, they can make a real difference
to the compile time.


Cheers,
Bob


* Just starting traversing the headers shipped with MSVC++,
including <string> also drags in ...

istream
ostream
ios
streambuf
xlocnum
cerrno
errorno.h
climits
limits.h
cstdio
stdio.h
cstdlib
stdlib.h
xiosbase
xlocale
cstring
string.h
stdexcept
exception
xstring
etc ...

So having <string> included twice may well cause an additional 20
or 30 file operations for _each_ client file which uses the
header with the duplicated include.



-----Original Message-----
From: Steve M. Robbins [mailto:ste...@vi...]
Sent: 25 September 2001 15:41
To: Cpp Unit Develpment Mailing List
Subject: Re: [Cppunit-devel] Duplicated #includes



Hello,

Sorry for being so dense this morning, but: do the duplicated includes
cause any trouble?


On Tue, Sep 25, 2001 at 02:30:33PM +0100, Summerwill, Bob wrote:
> Baptiste wrote ...
> 
> >> Shoudln't that <string> only be included if you don't have 
> >> CPPUNIT_HAVE_SSTREAM anyway ?
> 
> I'm not sure.  Presumably it's there so that the inline implementation
> of OStringStream::str() can construct the msg local variable, in which
> case you are probably correct.

Yeah, you're right, it could be protected.
 
> >> Wouldn't it be better to move the declaration of OStringStream in
> >> its one header (include/cppunit/portability, include/cppunit/tools ?),
> >> and includes it only where it is used ?

The whole reason for "Portability" is so that you can just
#include it, and then assume a whole bunch of things.  Like
class OStringStream is defined.  I would argue that including
<string> unconditionally in "Portability.h" is also a good thing.

It is true that at present, OStringStream is only used in a couple
of the CppUnit sources.  However, users that define their own
assertion_traits (i.e. ME!) also use OStringStream.  It is convenient
to include a single CppUnit header and have everything I need
defined.

As I said above: I don't understand the concern over a few extra
includes.

-Steve

-- 
by Rocket to the Moon,
by Airplane to the Rocket,
by Taxi to the Airport,
by Frontdoor to the Taxi,
by throwing back the blanket and laying down the legs ...
- They Might Be Giants


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