Inheritance and Method Lookup
Try it: Inheritance and Method Lookup
How a subclass inherits from its parent, how Python finds an attribute by walking the instance, then the class's method resolution order up to object, how overriding and super() work, why the same call does different things on different objects (polymorphism), and what isinstance / issubclass check.
How it works
- class Dog(Animal) gives Dog the MRO Dog → Animal → object; Puppy(Dog) gives Puppy → Dog → Animal → object.
- obj.name searches obj.__dict__, then each class of type(obj).__mro__ in order; the first class that defines the name wins, so a subclass method overrides the parent's.
- super().method() starts the search in the class after the one the current method was defined in, e.g. to run the parent's __init__.
- Calling the same method on a list of different objects runs each object's own version (polymorphism).
- isinstance(obj, C) is True when C is in type(obj).__mro__; if no class has the name, Python raises AttributeError.
Default run (63 steps): Ready: Animal, Dog, Cat and Puppy, then the statements you picked. Each attribute is searched along the class's MRO. … Finished. Printed: Rex the dog says Woof / Tom the cat says Meow / Bo the dog says Woof! / True / Puppy / Dog / Animal / object.
Simplified: The lab's own small Python interpreter runs a fixed, hand-written script (you choose the variant and the values, never the code); nothing is executed as real Python. Every script was run in CPython 3.12 with the same inputs and the lab reproduces its output and error messages. Single inheritance only (the lab's MRO code is Python's C3 algorithm, but no class here has two parents).
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