Extensions

This sheet explains how extensions work internally in the engine. We'll see how the get loaded, and what different hooks they provide.

We won't talk about how and why to write an extension.

As you should know, we distinguish between “PHP extensions” and “Zend extensions”. Consider this vocabulary to follow the article, as internally, the sources prefer talking about PHP extensions as “modules” and Zend extensions as “extensions”. We'll keep the more clear “PHP extension” vs “Zend extension” wordings.

Both extension kinds share lots of stuff. The difference between both types is mainly in hooks they register into the Engine.

All extensions may be built statically or dynamically. When built statically, the extension is loaded earlier than when its built dynamically and loaded throught php.ini. So, the first thing to remember is that an extension may behave differently if it is loaded statically against dynamically, at least if the maintainer has not taken care of such a behavior.