Error with simple subclassing of pathlib.Path: no _flavour attribute

Question

I\'m trying to sublclass Path from pathlib, but I failed with following error at instantiation

from pathlib import Path
class Pl(Path):
    def __init__(self         


        

Answer 1

Path is somewhat of an abstract class that is actually instantiated as on of two possible subclasses depending on the OS:

PosixPath or WindowsPath

https://docs.python.org/3/library/pathlib.html

This base class looks for an internal (private) class variable to determine what type of object it actually is, and this variable is called _flavour

You have two choices:

1. Derive your class from one of the concrete subclasses.
   This is the best choice as it will save you dealing with undocumented library internals and guarantee your code will not break on different versions of the library.
   You will need to define your class differently based on the OS if you want your code to be cross-platform.

The code will look like this:

import os

if os.name == 'posix':
    base = PosixPath
else:
    base = WindowsPath

class P1(base):
    def __init__(self, *pathsegments: str):
        super().__init__(*pathsegments)

2. Alternatively fill in the class variable yourself.
   This is not recommended as you will be using undocumented elements that could break at any time with any change to the library, but it will allow you to inherit from Path directly.

Note, there may be other issues if you decide to use this method!

import os
from pathlib import _PosixFlavour
from pathlib import _WindowsFlavour

class P1(Path):
    _flavour = _PosixFlavour() if os.name == 'posix' else _WindowsFlavour()

    def __init__(self, *pathsegments: str):
        super().__init__(*pathsegments)