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AttributeError: __metadata__ on Python 3.13 #303
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Pull request: #304
MRE
import sys from dataclasses import dataclass from typing import Literal from injector import Injector # Trigger: Python 3.13 + Literal + slots=True # In Python 3.13, the internal representation of Literal can sometimes # satisfy _is_specialization(v, Annotated) but lack the __metadata__ attribute. @dataclass(slots=True) class ServiceConfig: environment: Literal["prod", "test"] = "test" def reproduce(): print(f"Python version: {sys.version}") injector = Injector() print("Attempting to create object (this triggers get_bindings)...") try: # This will trigger the AttributeError on Python 3.13 with injector <= 0.23.0 injector.get(ServiceConfig) print("Success: No error raised.") except AttributeError as e: print(f"\nCRASH DETECTED: {e}") if "__metadata__" in str(e): print("Confirmed: This is the Python 3.13 __metadata__ regression.") except Exception as e: print(f"Unexpected error: {type(e).__name__}: {e}") if __name__ == "__main__": reproduce()- changed the title
[-]Compatibility with Python 3.13[/-][+]AttributeError: __metadata__ on Python 3.13[/+]on Jan 8, 2026
There is compatibility problem which raises the following exception:
which might be fixed by replacing:
in
__init__.pyfile with: