def — Expert Examples

Defines a new function or method

EasyIntermediateAdvancedExpert

Function objects and introspection

Examining function internals.

python
def example(x: int, y: str = "hello") -> bool:
    """An example function."""
    z = x + len(y)
    return z > 10

import dis
import inspect

# Signature
sig = inspect.signature(example)
print(f"Signature: {sig}")

# Annotations
print(f"Annotations: {example.__annotations__}")

# Code object
code = example.__code__
print(f"Variables: {code.co_varnames}")
print(f"Constants: {code.co_consts}")

# Bytecode
print(f"\nBytecode:")
dis.dis(example)

Functions are first-class objects with rich metadata: __code__ holds the compiled bytecode, __annotations__ holds type hints, and __doc__ holds the docstring. The dis module shows the bytecode instructions.

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