launchpad-users team mailing list archive

[Richard Wilbur <richard.wilbur@xxxxxxxxx>]

Here's my understanding of why:
The reason a version of source code is immutable in Launchpad PPA's is that
the package update infrastructure on every machine subscribed to your PPA
(apt & dpkg software and databases) need a way to upgrade when packages
change.  This is keyed solely off the version number ordering.  A
particular package version is synonymous with the version of source that it
was built from.  Thus a new version of source requires a new (subsequent)
version number (whether or not the source changes create any change in the
binary which is built).

If package version numbers didn't change with their contents everyone who
downloaded and installed your package before you updated the contents would
be using the old package and everyone who downloaded and installed after
you updated would be using the new package.  The rub is two-fold:  they
would both have the same package version number thus confounding debugging
efforts, those using the old contents would have no way to know there was a
better binary on the PPA nor any automated to update to it--they'd have to
manually uninstall, purge any package cache, download the new package (with
the same version number), and reinstall.

Sincerely,
Richard