Re: [Opalvoip-devel] PTLIBDIR: why is it necessary?

[Stefano S. <ssa...@re...>]

On date Friday 2008-10-03 10:30:23 +1000, Craig Southeren phoned this:
> Stefano Sabatini wrote:
> > Hi dear PTlib developers,
> > 
> > I wonder why is PTLIBDIR/PWLIBDIR necessary, assuming it has ever
> > been.
> 
> PTLIBDIR and OPALDIR are required to allow the use of PTLib and Opal in 
> non-standard locations
> 
> For example, on my Linux development machine, I have four different 
> versions of PTLib and Opal, and none of them are installed in the 
> standard location. I use PTLIBDIR and OPALDIR to point to the versions 
> that I need to use for the current project.

When you don't want to use the system library in a specific project a
good system is to include the libraries/headers within the project
itself.

CONTRIB_ROOT=contrib
CFLAGS="-I$(CONTRIB_ROOT)/include $(CFLAGS)"
LDFLAGS="-LS$(CONTRIB_ROOT)/lib $(LDFLAGS)"

If you have many version installed on your system and you just want to
pick up a selected, avoiding to include it for each one of the many
project which use it you can do something like this:

/opt/ptlib/1.13
/opt/ptlib/2.2
/opt/ptlib/2.4

then you can do inside your project:

PTLIB_VERSION=X.Y

PTLIB_CFLAGS=-I/opt/ptlib/$(PTLIB_VERSION)/include
PTLIB_LDLAGS=-L/opt/ptlib/$(PTLIB_VERSION)/lib

That's of course are just possible solutions, the first one which come
out from the top of my head.

> > My suggestion is to eliminate the need for it (which should somehow
> > simplify the build system), or in alternative at least to eliminate
> > the need for the redundant variable PWLIBDIR.
> > 
> > Yes if you like the idea I'll try to provide the patch.
> 
> I've just done a quick grep on the head revision of the trunk code, and 
> there are only two references to PWLIBDIR, and these are only for 
> backwards compatibility

My point is that having an env var for each possible library would be
a mess, furthermore having this var conflicts with the use of
pkg-config and other possibly better systems for automatic LDFLAGS
detection.

Best regards.
-- 
Stefano Sabatini
http://www.reilabs.com