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Python

Dynamic Typing Basics

Dynamic Typing¶

Overview¶

1. No Type Declarations¶

# No type needed
x = 42
x = "hello"  # Can change type
x = [1, 2, 3]  # Again

Runtime Type Checking¶

1. Type Determined at Runtime¶

def process(data):
    # Type checked when executed
    return data * 2

print(process(5))      # 10
print(process("hi"))   # "hihi"

Duck Typing¶

1. If It Walks Like Duck¶

class Duck:
    def quack(self):
        return "Quack!"

class Person:
    def quack(self):
        return "I'm quacking!"

def make_it_quack(thing):
    return thing.quack()

# Both work
print(make_it_quack(Duck()))
print(make_it_quack(Person()))

Summary¶

Types determined at runtime
No explicit declarations
Duck typing philosophy
Flexible but needs care