#pragma interface and #pragma implementation

["Steven T. Hatton" <hattons at globalsymmetry dot com>]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

I've been experimenting with the #pragma directives described in the following 
section of the GCC documentation:
http://gcc.gnu.org/onlinedocs/gcc-3.4.0/gcc/C---Interface.html#C++%20Interface

I'm not really sure how to use these. What I believe the document is saying is 
I should put `#pragma interface' in my 'header' files. 

I'm not sure of the placement of the directive relative #include directives.  
I expect the `#pragma interface' directive to influence the processing of any 
files #included after it appears.  I am not sure of the consequence of this 
on such items as the standard headers, or third party library headers.  
Should the `#pragma interface' be the first directive in the header file?

Should I have include guards in the headers using the `#pragma interface'?

For the sake of clarity I provide this example of an '#include guard:
#ifndef _INPUT_BOX_H_
#define _INPUT_BOX_H_
// C++ declarations go here
#endif

If I #include a header containing a '#pragma interface' directive in another 
header, do I need to do anything special such as use a `#pragma interface 
"filename.h"' directive?

In the source file I believe I should put directives of the form demonstrated 
by these: 

#pragma implementation "InputBox.h"
#include "InputBox.h"
#pragma implementation "Pragmatic.h"
#include "Pragmatic.h"

The only exception to this would be if my header and source share the same 
base name.  In that case `#pragma implementation' should suffice.  Is that 
correct?

Are there any examples of the use of these directive available online? Where?


- -- 
Regards,
Steven
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.2.2 (GNU/Linux)

iD8DBQFAvNw9wX61+IL0QsMRAmXYAKDNCObBgV1T5Mwk3tZD6gtuF9cR/ACfR2Al
Cdh5aCEU8jXnTpKdnRJ7S0M=
=Anen
-----END PGP SIGNATURE-----