Re: moving a file with template code to another directory breaks compile -- more info

[Paul Pluzhnikov]

u19809 <rc20683@chello.be> writes:

> I found in the meantime a way to make it compile but cannot explain why
> the workaround fixes things
>
> The code I had contains #pragma implementation and #pragma interface in
> the header file.  This matches my findings since these pragma's do
> something with respect to copying header information or not.

They don't do that.

What they do do is prevent creating of template instantiations
('#pragma interface') even when compiler could have created them.
The '#pragma implementation' undoes the effect of '#pragma interface'.

> So Question now remains why does the #pragma things break compile when the
> source file is in a different location as the header

Reading 'info gcc' reveals the answer:

     If you use `#pragma implementation' with no argument, it applies to
     an include file with the same basename(1) as your source file.
     For example, in `allclass.cc', giving just `#pragma implementation'
     by itself is equivalent to `#pragma implementation "allclass.h"'.

So the problem is not that you copied WxAction.cpp into a different
location (that would have worked); the problem is that you also
renamed that file to WxAction_A.cpp
 
Cheers,

P.S. You probably should remove these pragmas altogether -- they
probably provide minimal disk space savings (none in the final
executable, but some savings in intermediate object files), but
cause headaches and aren't portable either.
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