Meaning
This defines a function with explicit type annotations for its parameters and return value. It helps catch type mismatches early and makes the code self‑documenting, addressing the pain of hidden bugs in dynamically typed code. Use it whenever you need a reusable utility where input and output types should be clear.
Primary Function
Function definition
Communicative Purpose
Enables declaring a reusable code block with explicit type safety for arguments and return values.
Pattern
def function_name(parameter_name: parameter_type) -> return_type:
Core Structure
def ...(...) -> ...:
Função primária
Function definition
Propósito comunicativo
Enables declaring a reusable code block with explicit type safety for arguments and return values.
Situações de gatilho
Utility scripts: creating a small helper function Web APIs: defining an endpoint handler that returns a string response Data processing: writing a function to format output values
Contextos
Modern Python 3.5+ codebases, type-checked projects using mypy or pyright.
Padrão
def function_name(parameter_name: parameter_type) -> return_type:
Estrutura central
def ...(...) -> ...:
Slots de substituição
function_name: identifier, parameter_name: identifier, parameter_type: type, return_type: type
Colocados típicos
- return statement
- docstrings
- type imports from typing module
Substituições comuns
- Omitting type hints for quick scripts
- using Union or Optional for complex types
Erros comuns
Forgetting the colon, mismatching the actual return type with the hinted type, using mutable default arguments
Similar / contraste
Lambda functions (anonymous, single expression), functions without type hints (dynamic typing)
Interferências
Coming from JavaScript: Python requires 'def' and colons, not 'function' or arrows for standard definitions.
Família do chunk
- Function definitions
- lambda expressions
- type annotations
- decorators
Nuance
Type hints are not enforced at runtime by default; they require a static checker. Avoid over-using complex generics in simple scripts.
Efeito pragmático
Improves code readability, enables IDE auto-completion, and catches type errors before execution.
Dica de memória
The 'def' keyword starts the definition, colon ends the header, arrow points to the return type.
Nota
Type hints are optional but improve tooling support; they are not enforced at runtime without a static checker.
Upgrade path
Using *args, **kwargs, or Callable types for higher-order functions.
Log in to save chunks.