On Thu, 16 Apr 2009, Lorenzo Bettini wrote:
Never try to set the interface numbers so that they correspond to the release
number of your package. This is an abuse that only fosters misunderstanding
of the purpose of library versions. Instead, use the -release flag (see
Release numbers), but be warned that every release of your package will not
be binary compatible with any other release.
what I don't understand is the "not binary compatible": if I use, say 1.0 for
the release flag (and the version number correctly as stated in the manual),
and release another implementation of the library with the incremented
version number but with the same release number, why won't it be binary
compatible?
Or does "not binary compatible" apply only if I increment also the release
number?
I sense some confusion. :-)
The -release option specifies part of the base naming for your library
so that it becomes part of the base library name. For example,
libfoo-1.0.so and libfoo-2.0.so. To the operating system these
libraries are completely different and might have well been named
libfoo.so and libbar.so. The libraries might otherwise be entirely
the same and could be "binary compatible" but the operating system
won't know it. Very few packages use the -release option.
The -version-info option specifies library versioning information that
the operating system will use when deciding which similarly named
library to use. On most Unix systems, this forms the numeric part in
the library file name after ".so". Different systems use different
rules when deciding how to treat this version information. Assuming
that libraries are from the same release, the correct library will be
used as long as you follow the libtool rules when updating the
-version-info argument.
There are many forms of "binary compatible". For example, a newer
library might add a new function but otherwise be the same so an
already existing application (using an older library) can safely use
it. A newer application depending on the newer library could not
safely use the older library since it might be using the new function
the new function might not be present.
Bob
--
Bob Friesenhahn
bfrie...@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer, http://www.GraphicsMagick.org/
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