typing-utilities 0.0.1

Runtime reflection and validation of types and generics.

typing-utilities: Runtime reflection and validation of types and generics.

typing-utilities extends Python with the ability to check instances and types of generic types and unions introduced in the typing module.

Following is a small example of two of the most usable functions issubclass_typing and isinstance_typing, but a lot more is to be found in the API section further down...

Example:

from typing import Generic, TypeVar
from typingutils import issubclass_typing, isinstance_typing

T = TypeVar('T')

class Class1(Generic[T]):
    pass

class_type1 = Class1[str]
class_type2 = Class1[int]

issubclass_typing(class_type1, class_type2) # => False

# next line will fail
issubclass(class_type1, class_type2) # => TypeErrorr: Subscripted generics cannot be used with class and instance checks

class_inst1 = class_type1()
class_inst2 = class_type2()

isinstance_typing(class_inst1, class_type1) # => True
isinstance_typing(class_inst1, class_type2) # => False
isinstance_typing(class_inst2, class_type2) # => True
isinstance_typing(class_inst2, class_type1) # => False

# next line will fail
isinstance(class_inst1, class_type1) # => TypeError: Subscripted generics cannot be used with class and instance checks

Conventions

This project differs from Python and other projects in some aspects:

• Generic subscripted types like list[str] are always a subclass of its base type list whereas the opposite is not true.
• Any type is a subclass of type[Any].
• type[Any] is not an instance of type[Any].
• Builtin types and typing types are interchangeable, i.e. list[T] is interchangeable with typing.List[T] etc.

What's not included

Deep validation checks

This project does not check the contents of objects like lists and dicts, which is why isinstance_typing([1, 2, 3], list[int]) returns false. The reason is, that while it's relatively easy to compare every item in a list to the type argument of list[str], other generic types are not as straight forward, thus it's better left to the programmer.

Generic types

It's not the goal of this project to deliver generic types such as generically enforced lists and dicts.

API

Go to API documentation

Other similar projects

There are other similar projects out there like typing-utils and runtype, and while typing-utils is outdated and pretty basic, runtype is very similar to typing-utilities when it comes to validation.