Re: [Mingw-users] Multiple definition error

[Keith M. <kei...@us...>]

On Wednesday 17 May 2006 8:00 pm, Michael Gerdau wrote:
> > A cleaner approach [in Steve Pribyl's opinion] would be.
>
> I challenge that this is cleaner -- in particular for larger projects
> your suggestions easily gets out of hand. Or that's my experience.
>
> > utils.h
> > extern FILE *system_log_file;
> >
> > utils.c
> > FILE *system_log_file;
> >
> > No messy cpp code.
>
> Messy ?!?
> We will to disagree on that one.

Well, FWIW I too would do just as Steve suggests, except that in utils.c 
I would initialise system_log_file:

  #include "utils.h"
  :
  FILE *system_log_file = NULL;

which is then consistent with the OP's example.  Also, if this were in a 
sizeable project, I'd probably put utils.o into a project local library, 
for convenience in managing the build.

And yes, for this type of initialisation, C *is* less messy than C++ IMO, 
simply because C++ is complete overkill.  The caveat is that utils.h 
needs to make the declaration conditionally `extern "C"', if the project 
includes C++ modules which will use it, and, of course if utils.c needed 
to define some objects for which C++ would be more appropriate than C, 
then I would replace it with utils.cpp.

> Anyway, your proposal spreads definition and declaration across
> two files which is inferior in this regard.

Eh????  It's completely standard practice to separate declarations and 
definitions in this manner; *.h files *should* have declarations *only*, 
while definitions go in *,c or *.cpp files.  Unless you never use header 
files, then *you* must do this all the time.

Regards,
Keith.