Louis-Vincent Boudreault <lv.boudreaul...@gmail.com> added the comment:
Path.__new__ should not call _from_parts because it breaks the specialization
by directly using object.__new__.
This is why `_from_parts` has to be duplicated in each subclass's `__new__`.
My suggestion (first draft) is to do the parsing of arguments inside an
`__init__` in the Path class hierarchy
and deprecate `_from_parts`.
```
class PurePath:
def __new__(cls, *args):
if cls is PurePath:
cls = PureWindowsPath if os.name == 'nt' else PurePosixPath
super().__new__(cls, *args) # Here we remove call to from_parts
def __init__(self, *args):
# We should have an __init__ in the hierarchy.
drv, root, parts = self._parse_args(args) # this would get the proper
_flavour.
self._drv = drv
self._root = root
self._parts = parts
...
class Path(PurePath):
def __new__(cls, *args, **kwargs):
if cls is Path:
cls = WindowsPath if os.name == 'nt' else PosixPath
# REMOVE THIS LINE: self = cls._from_parts(args, init=False) #
if not self._flavour.is_supported:
raise NotImplementedError("cannot instantiate %r on your system"
% (cls.__name__,))
return super().__new__(cls, *args, **kwargs) # Use super
```
I don't know what is the purpose of `_init` and if it could be replaced by an
extra keyword argument in __init__.
The class method `_from_parts` would become deprecated since the argument
parsing would be now handled by `__init__`.
By using __init__ and avoid the direct call to `object.__new__` we would
respect class specialization and custom class could be implemented intuitively.
----------
nosy: +louis-vincent.boudre
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Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue41109>
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