I help moderate an emerging technologies forum on the TechSoup site--a technology for nonprofits company. A month ago, I made a short introductory post on the merits of using Drupal. It led to a discussion that included CiviCRM, upgrades, modules, WAMP, with a link to a good offsite introductory post by Dave Briggs.

Dave posted on TechSoup that one of the reasons that Drupal is a great tool is because you can hack the source to your heart's content.

PLEASE, DO NOT HACK CORE.

I wrote on the TechSoup forum the following response.

While it is quite possible to modify the source code in core, it isn't a good practice. There are a few reasons why.

1. Hack core and when you want to upgrade to a later version of Drupal, the experience can be nearly impossible.
2. If you decide to work with a Drupal developer after slugging away at it for a while and you've hacked core it is going to cost you. Developers will typically charge you to unhack the code and then will create a custom module (or use an existing module) to do what-ever it was you hacked core to do. Then they will get down to work on what you wanted them to do.
3. If you hack core, the huge community may not be able to answer your questions--the core software no longer matches that of the greater community making trouble shooting tough.

Interestingly, chx entered into the conversation pointing out that Drupal is for everyone so anyone should be able to contribute to it. If you are knowledgable, take a slow methodical approach to creating patches.

So, in general, please don't hack core. It is bad practice and can cause real difficulties down the road. It is much more sensible to create custom modules that over-ride core if there are behaviors you want to see changed.

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