Python 3.12+typesfunction

types.get_original_bases()

dynamic class creation

Returns the class bases as they were written in the class statement: Generic[T] instead of Generic. The ordinary __bases__ loses these details.

Syntax

types.get_original_bases(cls)

After __mro_entries__, __bases__ keeps only a bare Generic, and it no longer tells you with which type parameters the class was inherited. The function reads __orig_bases__ and falls back to __bases__ for classes without it. Serialisation and type-checking libraries need it to learn, for example, that Box inherits Generic[int].

Examples

# Python 3.12+
import types
import typing
T = typing.TypeVar('T')
class Box(typing.Generic[T]):
    pass
print(Box.__bases__)  # → (<class 'typing.Generic'>,)
print(types.get_original_bases(Box))  # → (typing.Generic[~T],)

See also

Open in the full glossarydocs.python.orgReport an inaccuracy