title: How easy is it to extend / modify Zend Framework?
body: <p>I've recently begun building version 2 of my year-old custom MVC framework. It's worked great for me on a number of projects, but I definitely see room for improvement. It's missing some major functionality like ACL, form validation, and caching. As much as I'd love to build those parts myself, I know that realistically it's not a smart decision. So, I've started looking at Zend Framework 1.9. I really like how its component library is loosely coupled. However, from looking at different tutorials, it seems very verbose. I've seen some sample applications that I could duplicate using less code with my own framework. As such, I'd like to "redefine" much of it to make it more RAD friendly. So before I invest a lot of time digging into the framework, I was hoping someone could shine some light on this subject for me. I'm a coder at heart, and have no problem spending hours upon hours tweaking and customizing something if it has a solid foundation (which I hope ZF has). </p>
  
  <p>I should note that I'm very happy to see that Doctrine can be integrated with ZF. </p>
  
  <p>If ZF isn't easily extendable, what other frameworks are (that also have ACL, form validation, caching)? I've been looking at Symfony, but the whole Configuration over Convention thing bothers me a lot.</p>
  
  <p>Thanks in advance for any input.</p>
  
  <p><strong>Edit</strong><br>
  To answer tharkun's question, what I mean by 'easily extendable' is that I can roll my own classes (that may or may not extend ZF classes) and package them in the framework so that I can easily build a foundation of code for my own projects. </p>