install() function if all you're going to do is to set the version of
the module from module.info into the database. This means that for some
simple modules, you don't need an install.php file at all.
Add xxx_installer::upgrade($version) method so that upgrade stanzas
are separate from install stanzas. In the old code, to do an upgrade
meant that you had to re-evolve everything from the initial install
because we'd step through each version's changes. But what we really
want is for the initial install to start off in the perfect initial
state, and the upgrades to do the work behind the scenes. So now the
install() function gets things set up properly the first time, and the
upgrade() function does any work to catch you up to the latest code.
See gallery_installer.php for a good example.
Install: <module>_installer::install() is called, any necessary tables
are created.
Activate: <module>_installer::activate() is called. Module
controllers are routable, helpers are accessible, etc. The module is
in use.
Deactivate: <module>_installer::deactivate() is called. Module code
is not accessible or routable. Module is *not* in use, but its tables
are still around.
Uninstall: <module>_installer::uninstall() is called. Module is
completely removed from the database.
Admin > Modules will install and activate modules, but will only
deactivate (will NOT uninstall modules).
