[issue42052] pathlib.Path should not call str() internally to allow inheritance

[conchylicultor]

conchylicultor  added the comment:

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()`

--
stage:  -> resolved
status: open -> closed

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[issue42052] pathlib.Path should not call str() internally to allow inheritance

[conchylicultor]

New submission from conchylicultor :

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

--
components: Library (Lib)
messages: 378710
nosy: conchylicultor
priority: normal
severity: normal
status: open
title: pathlib.Path should not call str() internally to allow inheritance
versions: Python 3.10

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