How to Use Type Hints for Multiple Return Types in Python
This function uses the Union type from the typing module to indicate that parse email returns either a string or None depending on the input value Whether you use the old or new syntax a union type hint can combine more than two data types Even when using a modern Python release you may still prefer the Union type over the pipe operator if your code needs to run in older Python versions
Union Type in Python The Complete Guide with Examples , Introduction to Union Type Introduced in Python 3 10 as part of PEP 604 Union Types allow a parameter variable or return value to be typed as one of multiple options Prior to 3 10 the typing Union was used Python 3 10 onwards the union operation can be performed using the operator
Typing Support for type hints Python 3 12 2 documentation
Typing Annotated Special typing form to add context specific metadata to an annotation Add metadata x to a given type T by using the annotation Annotated T x Metadata added using Annotated can be used by static analysis tools or at runtime At runtime the metadata is stored in a metadata attribute If a library or tool encounters an annotation Annotated T x and has no special
Python 3 10 Simplifies Unions in Type Annotations, The focus of this tutorial is to talk about PEP 604 which makes writing union types easier when adding type annotation AKA type hinting to your codebase Unions Ye Olde Way Before Python 3 10 if you wanted to say that a variable or parameter could be multiple different types you would need to use Union
PEP 484 Type Hints peps python
PEP 484 Type Hints peps python, Optional defined by Optional t Union t None Text a simple alias for str in Python 3 for unicode in Python 2 If in Python 3 you would omit some argument or the return type the Python 2 notation should use Any When using the short form for args and kwds
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26 1 typing Support for type hints Python 3 6 3 documentation
26 1 typing Support for type hints Python 3 6 3 documentation New features might be added and API may change even between minor releases if deemed necessary by the core developers This module supports type hints as specified by PEP 484 and PEP 526 The most fundamental support consists of the types Any Union Tuple Callable TypeVar and Generic For full specification please see PEP 484
Python Type Hint annotation with Typing Module
T U etc are type variables defined with TypeVar see below Objects classes defined with a class statement and instances are denoted using standard PEP 8 conventions the symbol applied to types in the context of this PEP means that two expressions represent the same type Note that PEP 484 makes a distinction between types and PEP 483 The Theory of Type Hints peps python. For functions where None can be returned you could use Union Type None however that can be unwieldy Instead there is the Optional type that specifies a value could be either the type or None from typing import List Optional T TypeVar T def get first item or none items List T Optional T return items 0 if items else None End I would personally go with Option 2 moving forward Also just wanted to add this for awareness but Python 3 7 can made to support this syntax using a future import as shown below This type checks just the same I actually got the tip from the latest release notes from Pycharm which I m currently using
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