Making class useable as a Path or str in python open function

I have a custom File class. I want to be able to pass it to the built-in open function like this:

f = File('./example.txt')
with open(f, 'rb') as fh:
    # read content as usual 

But this results in the error

TypeError: expected str, bytes or os.PathLike object, not File

MEDevel.com: Open-source for Healthcare and Education

Collecting and validating open-source software for healthcare, education, enterprise, development, medical imaging, medical records, and digital pathology.

Visit Medevel

The File class has a __str__ method which returns a string that can be used with open, so this works for me:

with open(str(f), 'rb') as fh:

But I want to use f directly. I tried inheriting it from Path but could not figure it out. Is there a simple way to make this work?

>Solution :

You need to create an os.PathLike object by adding an __fspath__ method that returns the path.

Example:

>>> class File:
...  def __fspath__(self):
...   return "C:\\temp"
...
>>> open(File())
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
PermissionError: [Errno 13] Permission denied: 'C:\\temp'

For more info, see the relevant documentation.