Type hints cheat sheet (Python 3) Type hints cheat sheet (Python 3) This document is a quick cheat sheet showing how the PEP 484 typeannotation notation represents various co...

Check that function returns a value [return] Check that function returns a value [return] If a function has a non-None return type, mypy expects that thefunction always explic...

Displaying error codes Displaying error codes Error codes are not displayed by default. Use —show-error-codes to display error codes. Error codes are shown inside square brack...

NewTypes NewTypes There are situations where you may want to avoid programming errors bycreating simple derived classes that are only used to distinguishcertain values from bas...

Using installed packages Using installed packages PEP 561 specifies how to mark a package as supporting type checking.Below is a summary of how to create PEP 561 compatible p...

Check list items [list-item] Check list items [list-item] When constructing a list using [item, …] , mypy checks that each itemis compatible with the list type that is inferred...

Advanced uses of self-types Restricted methods in generic classes Mixin classes Precise typing of alternative constructors Advanced uses of self-types Normally, mypy doesn’t...

Metaclass usage example Metaclass usage example Mypy supports the lookup of attributes in the metaclass: from typing import Type , TypeVar , ClassVar T = TypeVar (...

ORM Extensions ORM Extensions SQLAlchemy has a variety of ORM extensions available, which add additional functionality to the core behavior. The extensions build almost entire...

Check uses of various operators [operator] Check uses of various operators [operator] Mypy checks that operands support a binary or unary operation, such as+ or ~ . Indexing o...