computed #include directives questiron

[James]

I have a bunch of conditional #include statements like

#if PLATFORM == "LINUX"
#include "LinuxImplementation.h"
#elif PLATFORM ==" WINDOWS"
#include "WindowsImplementation.h"
#elif PLATFORM ==" MACINTOSH"
#include "MacintoshImplementation.h"
#endif

Is there some way I can use the standard preprocessor functionality to
transform this into a single #include stmt like

#include <PLATFORM "Implementation.h">

where 'PLATFORM' gets concatenated in front of "Implementation.h"?

My experiments with Microsoft's VC7 preprocessor have not been
successful so far.
Thanks!

[Victor Bazarov]

James wrote:

I have a bunch of conditional #include statements like

#if PLATFORM == "LINUX"
#include "LinuxImplementation.h"
#elif PLATFORM ==" WINDOWS"
#include "WindowsImplementation.h"
#elif PLATFORM ==" MACINTOSH"
#include "MacintoshImplementation.h"
#endif

Is there some way I can use the standard preprocessor functionality to
transform this into a single #include stmt like

#include <PLATFORM "Implementation.h">

where 'PLATFORM' gets concatenated in front of "Implementation.h"?

My experiments with Microsoft's VC7 preprocessor have not been
successful so far.

Provide a command-line macro that would be different on different
platforms similar to

-DPLATFORMIMPL2INCLUDE="\"LinuxImplementation.h\""

on Linux and

-DPLATFORMIMPL2INCLUDE="\"WindowsImplementation.h\" "

on Windows (and so on), and then do

#include PLATFORMIMPL2INCLUDE

in your code.

V
--
Please remove capital As from my address when replying by mail

[red floyd]

Victor Bazarov wrote:

James wrote:

I have a bunch of conditional #include statements like

#if PLATFORM == "LINUX"
#include "LinuxImplementation.h"
#elif PLATFORM ==" WINDOWS"
#include "WindowsImplementation.h"
#elif PLATFORM ==" MACINTOSH"
#include "MacintoshImplementation.h"
#endif

Is there some way I can use the standard preprocessor functionality to
transform this into a single #include stmt like

#include <PLATFORM "Implementation.h">

where 'PLATFORM' gets concatenated in front of "Implementation.h"?

My experiments with Microsoft's VC7 preprocessor have not been
successful so far.

Provide a command-line macro that would be different on different
platforms similar to

-DPLATFORMIMPL2INCLUDE="\"LinuxImplementation.h\""

on Linux and

-DPLATFORMIMPL2INCLUDE="\"WindowsImplementation.h\" "

on Windows (and so on), and then do

#include PLATFORMIMPL2INCLUDE

Couldn't he do something like:

#define HEADER_FILE_NAME PLATFORM "Implementation.h"
#include HEADER_FILE_NAME

[Victor Bazarov]

red floyd wrote:

Victor Bazarov wrote:

James wrote:

I have a bunch of conditional #include statements like

#if PLATFORM == "LINUX"
#include "LinuxImplementation.h"
#elif PLATFORM ==" WINDOWS"
#include "WindowsImplementation.h"
#elif PLATFORM ==" MACINTOSH"
#include "MacintoshImplementation.h"
#endif

Is there some way I can use the standard preprocessor functionality
to transform this into a single #include stmt like

#include <PLATFORM "Implementation.h">

where 'PLATFORM' gets concatenated in front of "Implementation.h"?

My experiments with Microsoft's VC7 preprocessor have not been
successful so far.

Provide a command-line macro that would be different on different
platforms similar to

-DPLATFORMIMPL2INCLUDE="\"LinuxImplementation.h\""

on Linux and

-DPLATFORMIMPL2INCLUDE="\"WindowsImplementation.h\" "

on Windows (and so on), and then do

#include PLATFORMIMPL2INCLUDE

Couldn't he do something like:

#define HEADER_FILE_NAME PLATFORM "Implementation.h"
#include HEADER_FILE_NAME

I don't think so. But do try it, and if you succeed, let us know.

V
--
Please remove capital As from my address when replying by mail

[red floyd]

Victor Bazarov wrote:

red floyd wrote:

Victor Bazarov wrote:

James wrote:
I have a bunch of conditional #include statements like

#if PLATFORM == "LINUX"
#include "LinuxImplementation.h"
#elif PLATFORM ==" WINDOWS"
#include "WindowsImplementation.h"
#elif PLATFORM ==" MACINTOSH"
#include "MacintoshImplementation.h"
#endif

Is there some way I can use the standard preprocessor functionality
to transform this into a single #include stmt like

#include <PLATFORM "Implementation.h">

where 'PLATFORM' gets concatenated in front of "Implementation.h"?

My experiments with Microsoft's VC7 preprocessor have not been
successful so far.
Provide a command-line macro that would be different on different
platforms similar to

-DPLATFORMIMPL2INCLUDE="\"LinuxImplementation.h\""

on Linux and

-DPLATFORMIMPL2INCLUDE="\"WindowsImplementation.h\" "

on Windows (and so on), and then do

#include PLATFORMIMPL2INCLUDE

Couldn't he do something like:

#define HEADER_FILE_NAME PLATFORM "Implementation.h"
#include HEADER_FILE_NAME

I don't think so. But do try it, and if you succeed, let us know.

V

Doh! You're right. I was thinking of the automatic concatenation of
strings by the compiler. Naturally the preprocessor would barf.

However, there may still be a way... If the OP isn't permanently in
love with having his PLATFORM in quotes.... e.g. instead of

#if PLATFORM=="Linux"

use

#if PLATFORM==Linux

Then can't we do something like the following?

DISCLAIMER: my memory of preprocessor quoting/evaluation is flaky.

#define str_(x) #x
#define str2_(x) str(x)
#define cat2_(x,y) x ## y
#define cat_(x,y) cat2(x,y)

#define PLATFORM_STRING str2_(PLATFORM)
#define HEADER_FILE str2_(cat2(PLATFORM, Implementation.h))
#include HEADER_FILE

[Dennis Jones]

"red floyd" <no*****@here.dude> wrote in message
news:k5*******************@newssvr11.news.prodigy. com...

However, there may still be a way... If the OP isn't permanently in
love with having his PLATFORM in quotes.... e.g. instead of

#if PLATFORM=="Linux"

use

#if PLATFORM==Linux

Then can't we do something like the following?

DISCLAIMER: my memory of preprocessor quoting/evaluation is flaky.

#define str_(x) #x
#define str2_(x) str(x)
#define cat2_(x,y) x ## y
#define cat_(x,y) cat2(x,y)

#define PLATFORM_STRING str2_(PLATFORM)
#define HEADER_FILE str2_(cat2(PLATFORM, Implementation.h))
#include HEADER_FILE

No. Part of how the preprocessor locates include files depends on how they
are included; that is, whether they are included as:

#include "somefile.h"
or
#include <somefile.h>

Your method will not work because it provides neither quotes nor brackets
(and as already stated, the preprocessor does not treat string-literals the
same way the compiler does).

- Dennis

[Dennis Jones]

"Dennis Jones" <no****@nospam.com> wrote in message
news:AVbag.5375$Sh3.690@trnddc05...

No. Part of how the preprocessor locates include files depends on how they are included; that is, whether they are included as:

Actually, much to my surprise, after some investigation and several typo
corrections, your method does indeed work:

#define str_(x) #x
#define str2_(x) str_(x)
#define cat_(x,y) x ## y
#define cat2_(x,y) cat_(x,y)

#define PLATFORM Windows
#define HEADER_FILE str2_(cat2_(PLATFORM, Implementation.h))
#include HEADER_FILE

Which results in:

Borland C++ Win32 Preprocessor 5.6.4 Copyright (c) 1993, 2002 Borland
file1.cpp:
Error E2209 file1.cpp 8: Unable to open include file
'WindowsImplementation.h'
*** 1 errors in Compile ***

- Dennis

[red floyd]

Dennis Jones wrote:

"Dennis Jones" <no****@nospam.com> wrote in message
news:AVbag.5375$Sh3.690@trnddc05...

No. Part of how the preprocessor locates include files depends on how

they

are included; that is, whether they are included as:

Actually, much to my surprise, after some investigation and several typo
corrections, your method does indeed work:

#define str_(x) #x
#define str2_(x) str_(x)
#define cat_(x,y) x ## y
#define cat2_(x,y) cat_(x,y)

#define PLATFORM Windows
#define HEADER_FILE str2_(cat2_(PLATFORM, Implementation.h))
#include HEADER_FILE

Which results in:

Borland C++ Win32 Preprocessor 5.6.4 Copyright (c) 1993, 2002 Borland
file1.cpp:
Error E2209 file1.cpp 8: Unable to open include file
'WindowsImplementation.h'
*** 1 errors in Compile ***

Remember, the unary # operator is the string-izer.

[Dennis Jones]

"red floyd" <no*****@here.dude> wrote in message
news:0C*******************@newssvr29.news.prodigy. net...

Dennis Jones wrote:

Actually, much to my surprise, after some investigation and several typo
corrections, your method does indeed work:

Remember, the unary # operator is the string-izer.

I know that -- I just didn't think about quotes being inserted implicitly.
Thus, I suppose if the OP wanted:

#include < ... >

....he'd be up a creek.

- Dennis

[red floyd]

Dennis Jones wrote:

"red floyd" <no*****@here.dude> wrote in message
news:0C*******************@newssvr29.news.prodigy. net...

Dennis Jones wrote:

Actually, much to my surprise, after some investigation and several typo
corrections, your method does indeed work:

Remember, the unary # operator is the string-izer.

I know that -- I just didn't think about quotes being inserted implicitly.
Thus, I suppose if the OP wanted:

#include < ... >

...he'd be up a creek.

- Dennis

Disclaimer: I haven't tested this. And it may not work.

#define STD_INCLUDE(x) cat2_(cat2_(<,x),Implementation.h>)

#include STD_INCLUDE(PLATFORM)

[Paul Mensonides]

red floyd wrote:

Disclaimer: I haven't tested this. And it may not work.

#define STD_INCLUDE(x) cat2_(cat2_(<,x),Implementation.h>)

#include STD_INCLUDE(PLATFORM)

This will error because the result of token-pasting must be a single token. In
any case, it doesn't matter because if a file is not found via the "file"
syntax, it is re-looked up as if it used the <file> syntax. This is required by
the standard. The reverse, however, is not the case.

Regards,
Paul Mensonides

[Phlip]

Paul Mensonides wrote:

This will error because the result of token-pasting must be a single
token.

This lovely hack might still work:

#define cat2_(a,b) a\
b

One wonders how legal it is... ;-)

--
Phlip
http://www.greencheese.us/ZeekLand <-- NOT a blog!!!

[Bo Persson]

"James" <du****@hotmail.com> skrev i meddelandet
news:11*********************@y43g2000cwc.googlegro ups.com...

I have a bunch of conditional #include statements like

#if PLATFORM == "LINUX"
#include "LinuxImplementation.h"
#elif PLATFORM ==" WINDOWS"
#include "WindowsImplementation.h"
#elif PLATFORM ==" MACINTOSH"
#include "MacintoshImplementation.h"
#endif

Is there some way I can use the standard preprocessor functionality
to
transform this into a single #include stmt like

#include <PLATFORM "Implementation.h">

where 'PLATFORM' gets concatenated in front of "Implementation.h"?

My experiments with Microsoft's VC7 preprocessor have not been
successful so far.
Thanks!

What about using literally #include "platform/implementation.h", and
supply a different 'platform' directory for each configuration?
Bo Persson

[Paul Mensonides]

Phlip wrote:

Paul Mensonides wrote:

This will error because the result of token-pasting must be a single
token.

This lovely hack might still work:

#define cat2_(a,b) a\
b

One wonders how legal it is... ;-)

It isn't. Or rather, it's legal but it won't do what you want. The result of
the should be 'ab' in all cases.

cat2_(1, 2) -> ab

Unfortunately, not all preprocessors implement the phases of translation as they
should.

Regards,
Paul Mensonides