typish 1.3.0

Functionality for types

Typish

• Functions for thorough checks on types
• Instance checks considering generics
• Typesafe Duck-typing

Installation

pip install typish

Content

Functions

Function	Description
subclass_of(cls: type, *args: type) -> bool	Returns whether cls is a sub type of all types in args
instance_of(obj: object, *args: type) -> bool	Returns whether cls is an instance of all types in args
get_origin	Return the "origin" of a generic type. E.g. get_origin(List[str]) gives list.
get_args	Return the arguments of a generic type. E.g. get_args(List[str]) gives (str, ).
get_alias	Return the typing alias for a type. E.g get_alias(list) gives List.
get_type	Return the (generic) type of an instance. E.g. a list of ints will give List[int].
common_ancestor	Return the closest common ancestor of the given instances.
common_ancestor_of_types	Return the closest common ancestor of the given classes.

Types

Type	Description
T	A generic Type var.
KT	A Type var for keys in a dict.
VT	A type var for values in a dict.
Empty	The type of emptiness (= Parameter.empty).
Unknown	The type of something unknown.
Module	The type of a module.
NoneType	The type of None.

SubscriptableType

This metaclass allows a type to become subscriptable.

Example:

class MyClass(metaclass=SubscriptableType):
    ...

Now you can do:

MyClass2 = MyClass['some args']
print(MyClass2.__args__)
print(MyClass2.__origin__)

Output:

some args
<class '__main__.MyClass'>

Something

Define an interface with typish.Something.

Example:

Duck = Something['walk': Callable[[], None], 
                 'quack': Callable[[], None]]

Anything that has the attributes defined in Something with the right type is considered an instance of that Something (classes, objects, even modules...).

The builtin isinstance is supported as well as typish.instance_of.