[development] Freezing the Drupal API

[Jeff Eaton]

> Sure, the code to do that doesn't look _really_ pretty and is a bit
hard 
> to grok, but at least it works and I don't have to patch a core file.

This is important.

Earlier in the thread, Dries asked if we came to Drupal because it
offered complete API support for every possible action, or because it
offered clean, easy-to-read code. I jumped on board the Drupal train for
neither of those reasons. :-) I'm here because Drupal allows me to
accomplish more WITHOUT MODIFYING THE CORE FILES than any other OSS
web-app framework I've worked with.

It's been noted that upgrading from one version of Drupal to another can
be tough. Having lived through epic migrations of PHPBB, PostNuke, and
Xoops, I can say that the BEST defense against painful upgrades is
isolating 'hacks' into modules. If those modules have to be reworked
when new versions come out, and the APIs they use shift, it's a pain.
But it's nowhere NEAR as much a pain as walking your way through  a
gigantic .diff, trying to figure out what hacked portions of node.module
you need to migrate over when 4.7 goes to 4.7.1.

--Jeff