LoadImage and SaveImage is unable to handle pathlib.Path

[Spenhouet]

Is your feature request related to a problem? Please describe.
For file handling (file paths) we are using the pathlib everywhere. In my experience this is great and helps with making paths OS independent.
When we work with MONAI this fails and we have to convert all paths to strings.

Describe the solution you'd like
LoadImage should be able to handle pathlib.Path objects as filename in addition to accepting strings.

def __call__(
    self,
    filename: Union[Sequence[str], str], # <- here
    reader: Optional[ImageReader] = None,
):

SaveImage should be able to handle pathlib.Path objects as output_dir in addition to accepting strings.

def __init__(
    self,
    output_dir: str = "./", # <- here

The easiest implementation is by simply accepting the pathlib.Path type and then converting it to string like str(my_path).

[Nic-Ma]

Hi @Spenhouet ,

Thanks for raising this topic.
Currently, only the PersistentDataset of MONAI supports pathlib.Path, all the other path related logic still work with string.
So I think if we want to add this support, we need to totally add for all the read/write components.
For example the image readers:
https://github.com/Project-MONAI/MONAI/blob/dev/monai/data/image_reader.py
@wyli @ericspod @rijobro , if you guys don't have any other comments, I will mark it as an enhancement request and welcome contribution.

Thanks in advance.

[Spenhouet]

I tested the fix and can confirm that it solved my issue.

[Spenhouet]

Thanks @wyli for the implementation. :)