From:	"John M. Aldrich" <fighteer AT cs DOT com>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Library Problem ! Help !
Date:	Sun, 14 Dec 1997 21:14:17 +0000
Organization:	Two pounds of chaos and a pinch of salt
Lines:	49
Message-ID:	<34944C29.5D7A@cs.com>
References:	<66v8v3$8s2$1 AT duke DOT telepac DOT pt>
Reply-To:	fighteer AT cs DOT com
NNTP-Posting-Host:	ppp243.cs.com
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To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

Hugo Jose Ferreira wrote:
> 
> My question is: HOW CAN I FIX THIS !!!! Maybe putting all the functions in
> the header file ISN'T the proper way of doing a library... But... my
> question is: how can I tell the linker to not include the functions I'm not
> using ?!?!?

Putting functions into header files is NEVER the proper way of doing a
library.  Gcc's linker always includes all code in each object file that
is passed to it into the final executable.  There is no way around this;
it's the way it's designed.

However, if you put the functions that you may or may not want linked
into a library in the proper way, then the linker will only link those
object files in the library that contain symbols that are used by your
code.  This means that in order to achieve maximum efficiency, you must
break your code down into individual source files, each of which
contains a single function and any local or static variables needed by
that function.

So, if you have functions "waitvretrace()" and "copyscr()" that you may
not want used in all your programs, you would split them up into source
files, like so:

  waitvret.c   (contains code for waitvretrace())
  copyscr.c    (contains code for copyscr())

Then you would compile them to object code:

  gcc -Wall -g -O2 -c waitvret.c
  gcc -Wall -g -O2 -c copyscr.c

Then you would put them into a library:

  ar rvs libmygfx.a waitvret.c copyscr.c

To link with the resulting library, use the following command line:

  gcc -Wall -g -O2 -o myprog.exe myprog.c -L. -lmygfx

Hope this helps!

-- 
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|      John M. Aldrich       | "Courage is the complement of fear.  |
|       aka Fighteer I       | A man who is fearless cannot be      |
|   mailto:fighteer AT cs DOT com   | courageous.  (He is also a fool.)"   |
| http://www.cs.com/fighteer |                    - Lazarus Long    |
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