Re: Dependency libraries and ABI

[Albert Chin <gtk-devel-list thewrittenword com>]

On Wed, Feb 27, 2002 at 12:13:54PM -0800, Keith Packard wrote:
> 
> Around 14 o'clock on Feb 27, Havoc Pennington wrote:
> 
> > This situation really sucks... what does Qt do about this? dlopen?
> 
> Qt hasn't faced Xft version 2 yet.  I have patches ready for them, but 
> they haven't merged.  Qt should have no problem with this; they support 
> printing with their API and apps don't generally go around the toolkit to 
> get at the underlying Xft library.

But you can build Qt 2.x and probably 3.x against libpng, zlib, mng,
jpeg, etc. So, these are dependencies on the Qt library. Same
situation that you're in with Xft and whatever other libraries you
link against.

As long as the libraries you link against have shared library names
following some sane fashion where major ABI changes are reflected in
the name of the library, what's the problem? If the dependent
libraries are built with libtool and they use and follow libtool's
-version-info switch, there shouldn't be a problem.

Of course, this is only for runtime. If someone upgrades one of the
dependent libraries so both now exist and attempt to rebuild an app,
the rebuild might not work due to an ABI incompatibility in the most
recent version.

-- 
albert chin (china thewrittenword com)