UserString subtypes parameterless `__init__`
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stdlib
type-feature
- Dominant language
- Python
- Stars
- 77.2k
- Forks
- 35.9k
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Description
Description
Subtypes of UserString cannot be initialized without a seq argument as the builtin str can.
Reproduction
from collections import UserString
class MyString(UserString):
pass
>>> str()
''
>>> MyString()
Traceback (most recent call last):
File "<python-input-2>", line 1, in <module>
MyString()
~~~~~~~~^^
TypeError: UserString.__init__() missing 1 required positional argument: 'seq'
Workaround
from collections import UserString
class MyString(UserString):
def __init__(self, seq: object = str()) -> None:
super().__init__(seq)
CPython versions tested on:
3.13
Operating systems tested on:
Linux
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start at the collections.UserString entry point and reproduce the parameterless-construction example on Python 3.13. Check the UserString initialization behavior and verify that a subclass without its own init can be instantiated like str(), while existing sequence initialization remains correct.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- python
- Domain
- backend
- Issue type
- Bug
- Difficulty
- 2/5
- Estimated time
- 1-3 hours
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 52/100