Python course / Working Python

Classes and objects

Keep data and the code that looks after it in one place, in classes that cannot be put into a broken state. Inheritance that reads perfectly in words and falls apart in code is the classic mistake here.

• __init__ and self
• methods
• repr
• equality
• inheritance
• composition
• properties
• one way in

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class Jar:
    def __init__(self, contents, grams):
        self.contents = contents
        self.grams = grams

    def __repr__(self):
        return f"Jar({self.contents!r}, {self.grams})"

    @property
    def is_empty(self):
        return self.grams == 0

    def take(self, grams):
        self.grams = max(0, self.grams - grams)


jar = Jar("honey", 340)
jar.take(340)
print(jar, "empty:", jar.is_empty)

Jar('honey', 0) empty: True