multiple inclusion of header files accross

multiple inclusion of header files accross

[Aaron Case]

Hello,

Is there a ld switch to address the problem of multiple inclusion of header
files accross object files.  I have used #ifndef and #define to prevent
multiple inclusion within an object file successfully.

Or should this be address in the makefile?  The current structure of the
makefile compiles several objects and then links the objects together but,
but some header files are included in almost all the source files used to
make each object.

Or should this be addressed by reorganizing my header files and throwing in
a few extern keywords?

Thanks in advance?

Aaron Case

Re: multiple inclusion of header files accross

[Eljay Love-Jensen]

Hi Aaron,

In typical C/C++ files, header files should not generate any bytes of output.  Declarations are okay, instantiated definitions are not.

 From Stroustrup's C++PL section 9.2.1

As a rule of thumb, a header may contain:
+ named namespaces
+ type definitions
+ template declarations
+ template definitions
+ function declarations
+ inline function definitions
+ data declarations
+ constant defintions
+ enumerations
+ name declarations (forward declarations)
+ include directives
+ macro definitions
+ conditional compilation directives
+ comments

Conversely, a header should never contain:
+ ordinary function definitions
+ data definitions
+ aggregate definitions
+ unnamed namespaces
+ exported template definitions

HTH,
--Eljay

RE: multiple inclusion of header files accross

[lrtaylor]

Aaron,

Are you experiencing problems that you believe is due to these multiple inclusions, or what is your main goal here that is driving you to get the number of inclusions down?

Thanks,
Lyle Taylor
IS Applications

-----Original Message-----
From: Aaron Case [mailto:aaron.case@dynazign.com]
Sent: Monday, September 15, 2003 1:12 PM
To: gcc-help@gcc.gnu.org
Subject: multiple inclusion of header files accross 

Hello,

Is there a ld switch to address the problem of multiple inclusion of header
files accross object files.  I have used #ifndef and #define to prevent
multiple inclusion within an object file successfully.

Or should this be address in the makefile?  The current structure of the
makefile compiles several objects and then links the objects together but,
but some header files are included in almost all the source files used to
make each object.

Or should this be addressed by reorganizing my header files and throwing in
a few extern keywords?

Thanks in advance?

Aaron Case