Make and speak as a dog
Input
create_animal('dog', 'Rex').speak()
Output
Rex says woof
create_animal returns a Dog instance. speak() returns a string using the instance name and the dog's sound.
Full lesson preview
Create an Abstract Base with Concrete Subclasses
Define an abstract base class and implement multiple concrete subclasses that follow the required interface.
Python practice15 minInheritance & PolymorphismIntermediateLast updated April 8, 2026
Problem statement
You must design an abstract Animal base class that enforces a speak() method. Implement three concrete subclasses (Dog, Cat, Bird) that provide specific speak() implementations. Also write a factory function create_animal(kind, name) that returns an instance of the appropriate subclass. The factory should be case-insensitive for kind and default the name to 'Unknown' if an empty string is given.
Task
Implement an abstract Animal base class with concrete Dog, Cat, and Bird subclasses plus a factory function that creates them. Ensure names default correctly and kind matching is case-insensitive.
Examples
Input format
Function-style calls. Example: create_animal('cat', 'Mittens').speak()
Output format
Return the string produced by calling speak() on the created instance.
Constraints
Do not change the names of the classes or the create_animal function. The factory must accept case-insensitive kinds. If name is empty, use 'Unknown'.
Samples
Sample 1
Input
create_animal('bird', 'Tweety').speak()
Output
Tweety says tweet
Birds say 'tweet' in this exercise.