What one would normally do in idiomatic dynamically typed Python code.Ĭhanged in version 3.10: Optional can now be written as X | None. To be explicitly marked to support them, which is unpythonic and unlike The problem with this approach is that a class had This requirement previously also applied to abstract base classes, such as This means that a class A is allowed whereĪ class B is expected if and only if A is a subclass of B. Initially PEP 484 defined the Python static type system as using Use Any to indicate that a value is dynamically typed. Use object to indicate that a value could be any type in a typesafe # Passes type checking, since ints and strs are subclasses of object hash_a ( 42 ) hash_a ( 'foo' ) # Passes type checking, since Any is compatible with all types hash_b ( 42 ) hash_b ( 'foo' ) def hash_b ( item : Any ) -> int : # Passes type checking item. Vector and list will be treated as interchangeable synonyms:ĭef hash_a ( item : object ) -> int : # Fails type checking an object does not have a 'magic' method. PEP 655: Marking individual TypedDict items as required or potentially missingĪ type alias is defined by assigning the type to the alias.PEP 612: Parameter Specification Variables.Introducing types.UnionType and the ability to use PEP 604: Allow writing union types as X | Y.PEP 593: Flexible function and variable annotations.

PEP 591: Adding a final qualifier to typing.

PEP 589: TypedDict: Type Hints for Dictionaries with a Fixed Set of Keys.

Introducing types.GenericAlias and the ability to use standard

PEP 585: Type Hinting Generics In Standard Collections.

PEP 544: Protocols: Structural subtyping (static duck typing).

Introducing syntax for annotating variables outside of function

PEP 526: Syntax for Variable Annotations.

Number of PEPs have modified and enhanced Python’s framework for type Since the initial introduction of type hints in PEP 484 and PEP 483, a The documentation at serves as useful referenceįor type system features, useful typing related tools and typing best practices.

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