Repository navigation
Document that inspect.isclass returns False for GenericAlias instances #132467
Description
Bug report
Bug description:
Hi
I am not sure if this is a bug, but I use the bug template because I couldn't find a better one to submit questions like this one.
The documentation says, "User-defined generic classes can be instantiated.".
import inspect
from typing import TypeVar, Generic
T = TypeVar("T")
class Node(Generic[T]):
x: T # Instance attribute (see below)
def __init__(self, label: T | None = None) -> None:
self.label = label
x = Node("") # Inferred type is Node[str]
y = Node(0) # Inferred type is Node[int]
z = Node() # Inferred type is Node[Any]
# Also OK:
y = Node[int](0)
print(inspect.isclass(Node)) # True
print(inspect.isclass(Node[int])) # False (shouldn't this be True?)
print(inspect.isclass(Node[str])) # False (shouldn't this be True?)In the example above, shouldn't calls such as inspect.isclass(Node[int]) return True, since they can be instantiated and used like normal classes?
CPython versions tested on:
3.13
Operating systems tested on:
Linux
Linked PRs
- gh-132467: Add test case to check whether GenericAlias instance is not class, update docstring of
typing._GenericAlias#133504 - [3.15] gh-132467: Document and test that generic aliases are not classes (GH-133504) #150854
- [3.14] gh-132467: Document and test that generic aliases are not classes (GH-133504) #151116
- [3.13] gh-132467: Document and test that generic aliases are not classes (GH-133504) #151117
Metadata
Metadata
Assignees
Projects
- Status
- Status
Activity
AbduazizZiyodov commentedon Apr 13, 2025
@sobolevn Can you assign me to this issue ? I will work on it
sobolevn commentedon Apr 13, 2025
@AbduazizZiyodov sure, please go ahead :)
AbduazizZiyodov commentedon May 3, 2025
isinstance(Node[int], GenericAlias)is also returningFalse:Version:
Python 3.14.0a7+, is that expected behaviour?AbduazizZiyodov commentedon May 3, 2025
But this behaves as expected:
I see that, there was discussion about
types.GenericAliasVStyping._GenericAlias. As I understand this is documented in code, should we document in online docs ?AbduazizZiyodov commentedon May 6, 2025
PRs #133504 , python/typing#1993
gh-132467: Document and test that generic aliases are not classes (#1…
[3.15] gh-132467: Document and test that generic aliases are not clas…
[3.14] pythongh-132467: Document and test that generic aliases are no…
[3.13] gh-132467: Document and test that generic aliases are not clas…
[3.14] gh-132467: Document and test that generic aliases are not clas…
pythongh-132467: Document and test that generic aliases are not class…
Merge pull request #1 from rohitjain25/clarify-generic-alias-isclass-…