Python Jumpstart by Building 10 Apps Transcripts
Chapter: App 7: Wizard Battle App
Lecture: Introduction to the Wizard Battle App

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0:00 It's time for app number 7,
0:03 and this time we are going to build a really fun wizard game
0:05 it's kind of a role playing dungeons and dragons sort of thing.
0:09 So what is that going to look like?
0:12 Well, it's going to be a text based game
0:14 and here you can see a standard ground of game play.
0:16 Of course, like all of our apps we start with a little header that says what the app is,
0:19 and then right off we have our hero in the game, the wizard Gandolf.
0:23 And he sees an Evil Wizard,
0:25 it turn out that one is super strong
0:27 and so he is like I am not going to battle this, he could attack it,
0:30 he could look around, but he is just going to run away as quick as he can,
0:33 so he does, and then next he finds a Bat, and decides
0:37 hey, I can probably attack and kill this Bat, so he does,
0:40 but just barely he roles a 22, the bat roles at 22
0:44 and I guess because the element of surprise
0:46 the wizard was triumphant over the Bat.
0:48 After that, the wizard Gandolf decides to have a look around
0:52 and he sees that there is a wimpy toad, a tiger, a dragon
0:55 and that very strong evil wizard hanging around.
0:58 The game goes around and around like this,
1:00 until either all the creatures are defeated or the wizard is gone.
1:04 While building this game we are going to learn
1:06 one of the most important concepts in all of computer programming
1:10 and that is the concept of object oriented programming.
1:14 This starts with defining classes
1:16 and classes defined how data and behavior
1:18 are bundled into one concept in programming
1:21 maybe this is a wizard or a dragon
1:24 or the general concept of a creature
1:26 or even the concept of a game itself.
1:29 When we create these classes, these are called objects,
1:31 we want to initialize them,
1:32 have them come into existence immediately with the data they need,
1:35 we'll do that through initializers
1:37 and when we are talking about inheritance
1:39 we have to chain those initializers through the inheritance tree,
1:41 so we are going to talk about initializer chaining.
1:44 Speaking of inheritance, that lets us model our concepts
1:47 in our program with different levels of specialization,
1:51 so we can model all of the actors, the dragon, the toad, the wizard
1:55 as something maybe we'll call the creature in the game
1:58 and then we have a specialized version of the creature
2:00 that has other data and other features called the wizard
2:03 and it knows how to battle creatures
2:05 and then we can also have different types of creatures
2:07 that may themselves have special features
2:09 like a dragon that has a special attack or something like that,
2:12 so this is called inheritance and it's a very powerful feature, when use judiciously.
2:16 When we talk about inheritance,
2:18 we are also going to talk about polymorphism and duck typing.
2:21 Some languages have very strict rules
2:23 about how you can use the more general what you call a base class
2:26 or the specialized derived class,
2:29 like how you can use a creature versus how to use a wizard,
2:32 the compiler checks all these things and so on,
2:34 Python doesn't have compiling or this concept of strong typing
2:37 instead we are going to use something called duck typing
2:40 we'll talk about that near the end of our app.
2:43 Let's get onto build a super fun dungeons and dragon style wizard game.