macro definition contains #include directive

**Pawel Dziepak** · Nov 5 '08, 08:25 PM

Re: macro definition contains #include directive

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Bing wrote:

Is there a way to define a macro that may contain #include
directive in its body. If I just put

<snip>

No, preprocessor directives in C++ (and C) are not reflective.

Pawel Dziepak

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**Noah Roberts** · Nov 5 '08, 09:35 PM

Re: macro definition contains #include directive

Bing wrote:

Hi folks,
Is there a way to define a macro that may contain #include
directive in its body. If I just put
the "#include", it gives error C2162: "expected macro formal
parameter" since here I am not using
# to concatenate strings. If I use "\# include", then I receive the
following two errors:
>
error C2017: illegal escape sequence
error C2121: '#' : invalid character : possibly the result of a macro
expansion
>
Any help?

Look at the boost preprocessor metaprogramming library. The
BOOST_PP_ITERAT E() macro is able to do it. See what it's doing or maybe
just use it.

**Pawel Dziepak** · Nov 5 '08, 09:45 PM

Re: macro definition contains #include directive

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Noah Roberts wrote:

Look at the boost preprocessor metaprogramming library. The
BOOST_PP_ITERAT E() macro is able to do it. See what it's doing or maybe
just use it.

Macro can be an argument of #include directive and that's how
BOOST_PP_ITERAT E() is used in boost (it's probably the solution for
Bing's problem). However, macro can't contain #include directive.

Pawel Dziepak
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**Bing** · Nov 5 '08, 10:25 PM

Re: macro definition contains #include directive

On Nov 5, 4:38 pm, Pawel Dziepak <pdzie...@quarn os.orgwrote:

>
Noah Roberts wrote:

Look at the boost preprocessor metaprogramming library. The
BOOST_PP_ITERAT E() macro is able to do it. See what it's doing or maybe
just use it.

>
Macro can be an argument of #include directive and that's how
BOOST_PP_ITERAT E() is used in boost (it's probably the solution for
Bing's problem). However, macro can't contain #include directive.
>
Pawel Dziepak

Thanks for the answers. Just let you know I started a topic on this at
stackoverflow.c om

macro definition containing #include directive

http://stackoverflow.com/questions/266501/macro-definition-containing-include-directive

Is there a way to define a macro that contains a #include directive in its body? If I just put the "#include", it gives the error C2162: "expected macro formal parameter" since here I am not usin...

**James Kanze** · Nov 6 '08, 08:45 AM

Re: macro definition contains #include directive

On Nov 5, 9:06 pm, Bing <bing.j...@gmai l.comwrote:

Is there a way to define a macro that may contain #include
directive in its body. If I just put the "#include", it
gives error C2162: "expected macro formal parameter" since
here I am not using # to concatenate strings. If I use "\#
include", then I receive the following two errors:

error C2017: illegal escape sequence
error C2121: '#' : invalid character : possibly the result of a macro
expansion

Any help?

No. After expansion, "the resulting completely macro-replaced
preprocessing token sequence is not processed as a preprocessing
directive even if it resembles one" [§16.3.4/3]. In other
words, even if there were a way of introducing a sequence
"#include" in the expansion, it wouldn't be an include
directive.

What problem are you trying to solve with this?

--
James Kanze (GABI Software) email:james.kan ze@gmail.com
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**Pascal J. Bourguignon** · Nov 6 '08, 11:45 AM

Re: macro definition contains #include directive

Bing <bing.jian@gmai l.comwrites:

Hi folks,
Is there a way to define a macro that may contain #include
directive in its body. If I just put
the "#include", it gives error C2162: "expected macro formal
parameter" since here I am not using
# to concatenate strings. If I use "\# include", then I receive the
following two errors:
>
error C2017: illegal escape sequence
error C2121: '#' : invalid character : possibly the result of a macro
expansion
>
Any help?

It is not possible with cpp, however it's trivial to do with make and
sed (or awk or anything else):

-----------(Makefile)--------------------------

example.c : example.cm
sed -e 's/EXPAND(\(.*\))/@#define SOMEVAR 1@#include <\1.h>@#defin e SOMEVAR_\1 2@/g' < example.cm \
|tr '@' '\012' example.c

# ...
-----------------------------------------------

----------(example.cm)-------------------------
/* -*- mode:c -*- */

EXPAND(ModuleA)

EXPAND(ModuleB)

/**** THE END ****/
-----------------------------------------------

Then typing make example.c will generate the file:

-------------(example.c)------------------------------
/* -*- mode:c -*- */

#define SOMEVAR 1
#include <ModuleA.h>
#define SOMEVAR_ModuleA 2

#define SOMEVAR 1
#include <ModuleB.h>
#define SOMEVAR_ModuleB 2

/**** THE END ****/
-------------------------------------------------------

--
__Pascal Bourguignon__