Stuart Herbert has two new posts to his blog showing how to use the ContractLib tool he's created to define programming "contracts". In the first he shows some sample usage of the tool and in the second he compares the functionality of ContractLib's features and PHP's own "assert" method.

ContractLib is a simple-to-use PHP component for easily enforcing programming contracts throughout your PHP components. These programming contracts can go a long way to helping you, and the users of your components, develop more robust code.

In his example tests he shows how to set a pre-condition on a method's input ensuring that it will always be the correct datatype (array). In his comparison with PHP's "assert", he lists out some of the features that either one has and notes that ContractLib allows you to be much more flexible with your checking than just simple statements.