DevShed: PHP Object Oriented Programming using LSP

- (phpdeveloper) - 10 months, 2 weeks ago...

In another part of their series looking at the SOLID principles of software development, DevShed focuses again on using LSP (the Liskov Substitution Principle) to help you organize your application (part one is here). Even though its formal definition is somewhat hard to grasp, in practical terms it states that methods defined in a base class (or interface) and their derivatives must have the same signature, preconditions should be weakened in the formers, and post-conditions should be st...