classification
Title: pathlib.Path should not call str() internally to allow inheritance
Type: Stage: resolved
Components: Library (Lib) Versions: Python 3.10
process
Status: closed Resolution:
Dependencies: Superseder:
Assigned To: Nosy List: conchylicultor
Priority: normal Keywords:

Created on 2020-10-16 10:48 by conchylicultor, last changed 2020-10-16 13:47 by conchylicultor. This issue is now closed.

Messages (2)
msg378710 - (view) Author: Etienne POT (conchylicultor) * Date: 2020-10-16 10:48
I'm writing a subclass of `pathlib.Path` with custom `__fspath__`.

To prevent bad usages (users should use `os.fspath(path)` instead of `str(path)` to access the underlying path), I would like to overwrite `str`:


```
class MyPath(pathlib.PosixPath):

  def __fspath__(self) -> str:
    # Custom fspath

  def __str__(self) -> str:
    raise TypeError(
        f'Please do not use `str()` directly:'
        ' * For display: Use, f-string, `.format` or `repr`'
        ' * To access the path string: Use `os.fspath`, as per PEP 519'
    )

  def __format__(self, format_spec) -> str:
    return format(super().__str__(), format_spec)
```

However, this is breaking pathlib internal, as `str(self)` is used at many places. It would be nice if all internal `str()` calls where replaced by some `self._str()`.

I also think it would be more semantically correct if some of the `__str__` call where replaced by `__fspath__`, like: https://github.com/python/cpython/blob/b30934e9afb0af3f8e2e5f0992445be775b3c630/Lib/pathlib.py#L748
msg378713 - (view) Author: Etienne POT (conchylicultor) * Date: 2020-10-16 13:47
Closing this as I realize that even if this was solved, it would still not fully resolve the issue. Basically I want to control how __fspath__ and __str__ behave externally (for users), but internal fspath and str should always call `super()`
History
Date User Action Args
2020-10-16 13:47:15conchylicultorsetstatus: open -> closed

messages: + msg378713
stage: resolved
2020-10-16 10:48:40conchylicultorcreate