Python for Entrepreneurs Transcripts
Chapter: Appendix: Python language concepts
Lecture: Concept: objects vs. classes
0:01 When you are new to object-oriented programming,
0:03 the idea of classes and objects often can seem interchangeable
0:07 and some people use them interchangeably; that's not really correct
0:12 and so let's take just a moment and really clarify the relationship
0:15 and differences between classes and objects.
0:18 So here we have a Creature class, you can it has an initializer and a walk method,
0:23 and notice that the walk method does something different if the creature is powerful,
0:27 if its power is greater than 10 versus if it's lower.
0:30 This class is a blueprint for creating creatures.
0:34 We could create a squirrel, we could create a dragon,
0:37 we could create a tiger, and those would all be specific
0:40 objects or instances of the Creature class.
0:43 So down here we’re going to create a squirrel and a dragon,
0:46 and notice the squirrel is created with power 7, the dragon is created with power 50.
0:50 Now these are both creatures, but they are now distinct things in memory.
0:55 Objects are created via classes and the squirrel object is somewhere in memory
1:00 and it has a power 7 and it has this walk behavior it gets from its class,
1:03 but all of its variables are specific to it.
1:07 We have also the dragon creature, with its own variables,
1:10 so it's power is 50 and if we change its power, it won't change the squirrel
1:13 or any other creature, just the dragon.
1:15 And when we call squirrel.walk(), the squirrel is going to walk in some specific way
1:19 based on its own power.
1:22 So you can see the Creature class test is a power greater than 10 or less than 10
1:26 and if it's greater than 10, it does something special,
1:29 maybe it walks in a powerful way versus a non-powerful way, who knows,
1:32 but that will mean the squirrel walks in one way
1:35 and the dragon walks in another way,
1:38 even though they are both instances of the Creature class.
1:40 So I hope that clears up the relationship between classes and objects.