5. The init method

5.1. The __init__() method

The __init__() method is a built-in-method that is used to assign values to object attributes, and to do other operations that are necessary when the object is created.
The __init__() function is called automatically every time the class is called when creating a new object.
The first parameter in the __init__() function is self, referring to the object itself.
Other parameters can follow self. e.g. __init__(self, level)
These other parameters, such as level, are passed in as arguments when the class is called.
e.g. game = LevelGame(level=1) passes in level=1 to the __init__() function.
game = LevelGame(1) and game = LevelGame(level=1) do the same thing.
e.g. game = LevelGame(level=1, lives=3) passes in level=1 and lives=3 to the __init__() function.
In the sample code, two instance variables, game_level and player_lives, are created.
class LevelGame:
    def __init__(self, game_level, player_lives):
        self.game_level = game_level
        self.player_lives = player_lives

game = LevelGame(game_level=1, player_lives=3)

Tasks

  1. Modify the code so that the game level starts at level 0 with 5 lives.

  2. Modify the code so the parameters and the instance variables have matching names.

  3. Modify the code by adding a third instance variable using a parameter called level_score and initialize it to 0.

5.2. *args in the __init__() function

To enable multiple values to be passed to the class Enemies, *args can be used for the parameter.
*args packs all the arguments into one single variable that can be treated like a normal tuple.
e.g enemies = Enemies(1, 2, 3) instantiates Enemies with 3 different enemies_levels.
class Enemies:
    def __init__(self, *args):
        self.enemy_levels = args


enemies = Enemies(1, 2, 3)
print(enemies.enemy_levels)

Tasks

  1. Test the Enemies example above by printing the enemy levels using the instance attribute for the enemy_levels.