The inspect module exposes signatures, parameters, annotations, and other information about Python objects. It helps with small frameworks, dependency injection, documentation, and adapter validation.
Practical example
from inspect import Parameter, signature
def send(message: str, *, urgent: bool = False) -> None:
pass
sig = signature(send)
for name, parameter in sig.parameters.items():
required = parameter.default is Parameter.empty
print(name, parameter.kind, required)Work with Signature
signature() and bind() model actual call rules, including positional, keyword-only, and variadic parameters. Compare a default with Parameter.empty; None may be a legitimate default.
Introspection has limits
Some native objects or wrappers do not preserve a complete signature. Use functools.wraps in decorators, avoid private attributes, and keep an explicit fallback for objects that cannot be inspected.
Keep learning
Continue with Python Decorators: Complete Guide and Python Type Hints: Complete Static Typing Guide. A official Python documentation, accessed July 22, 2026, documents the API and behavior across versions.