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PHP Using PHP with MySQL Connecting PHP to MySQL Introducing Classes

Posted by thomascawthorn
thomascawthorn
22,986 Points

Has anyone got a really good analogy or simple explanation for what a 'class' is?

I'm referring to this PHP video, but I've got a feeling I came across it in Rails too..

Randy describes it in this video but I can't quite wrap my head around it. Can anyone help me out with an alternative description?

1 Answer

Andrew McCormick
Andrew McCormick
17,730 Points
Andrew McCormick
Andrew McCormick
17,730 Points

Kind of the cliche example but suppose you are building houses, a class is like starting with a blueprint. If you decide to have both three- and four-bedroom houses, you can start with a blueprint (aka a class) called the house blueprint that has a ground floor and a second floor, but has no indoor walls drawn on the second floor. Then, you make two more secondfloor blueprints — one for the three-bedroom house and another for the fourbedroom house. (You name these new blueprints the three-bedroom house blueprint and the four-bedroom house blueprint.) So these other blueprints called 'three-bedroom' and 'four-bedroom' only describe the second floor, because they reference back to (or extend) the house blueprint which contains the info for the ground floor and the exterior of the second floor. So now rather than recreating all the directions for building the initial structure of a house, you can use your class (aka blueprint) to create many houses from one set of instructions.

class reference image

*partially taken from Java For Dummies

thomascawthorn
thomascawthorn
22,986 Points

This is fantastic! Thank you :)

So the class is a framework/blueprint to create objects - it tell objects what methods and properties it should include - but can you add properties and methods to an object that has been created from a class? i.e. customize it?