Question

I need to create some base exception classes and inherit from it.

I see two approaches:

1. Create folder 'Exceptions' in library and use standard autoload mechanism
    /library
      /Exception/
        Base.php
        InvalidParameter.php
2. Just declare exception classes in model, that uses it.

Is there a better more “Zend-ish” approach?

Answer 1

If you look into zend library, what they normally do is

/library
   Exception.php
  /Exception/
    InvalidParameter.php

And InvalidParameter Class would look something like Exception_InvalidParameter extends Exception. It is quite similar to what you have suggested in option 1.
I generally love to have all my custom library classes in to /library/custom