Mkdocs gallery and sys.path

[Louis-Pujol]

Hello,

I have a little issue with sys.path and mkdocs-gallery. I realized that changes to sys.path were not persistent across code blocks. Here is a simple illustration script :

"""
PYTHONPATH
==========
"""

# %%
# Copy python path

import sys
original_path = sys.path.copy()


# %%
# Append path and print new path directories

sys.path.append("/home/mypath")
new_path = sys.path.copy()
for p in new_path:
    if p not in original_path:
        print(p)


# %%
# Print new path directories

path2 = sys.path.copy()
for p in path2:
    if p not in original_path:
        print(p)

And the resulting example:

sys.path Were reinitialized between block 2 and block 3 as /home/mypath is no longer inside sys.path.This behavior comes from this function, which is called between blocks and reset sys.path:

https://github.com/smarie/mkdocs-gallery/blob/d4c2d7fd7991a590abc2c947a61334b3a56ab9f7/src/mkdocs_gallery/gen_single.py#L731-#L735

This caused me some trouble because I use some libraries that add cache directories to sys.path. If I understand correctly the purpose of _reset_cwd_path, it is meant to remove cwd from sys.path, but it actually removes all new additions.

In this PR, I propose to modify _reset_cwd_path in order to remove only the last cwd and do not erase other modifications to sys.path. With this new version, my example works as I expected:

Let me know what are your thoughts about this changes.
Many thanks,
Louis

[smarie]

Thanks @Louis-Pujol for this proposal !
I made a few readability comments (although the original sphinx-gallery code is not the best in readability, but we can at least marginally add comments)

Could you please also add a changelog entry for your mod ? Thanks !

[Louis-Pujol]

Thanks, I committed your suggestions.

I'm not sure about what I need to do for adding a changelog entry. Do I need to create a new release on my repository ? And if yes, which tag do I need to choose ? Sorry if my questions are naive, I'm not very familiar with those things

[smarie]

Thanks @Louis-Pujol . No, simply modify the file docs/changelog.md : add a bullet point in the first section (0.7.9 - (In Progress)) stating your contribution. You can follow the example that is already there

[Louis-Pujol]

Thanks, I just did it.

[smarie]

Thanks @Louis-Pujol . Now I had some afterthought: we do not want any sys path leak to happen between one example file and the others.

So now that sys path is preserved across blocks of a single example, we have to reset the sys path when the example is completed. Could you please modify parse_and_execute (that is calling all the execute_code_block) so that original sys path is copied before the loop, and it is reset after the loop ? That should do the trick.

Thanks a lot !

[smarie]

Suggested change

	- Rewrited `gen_single._reset_cwd_syspath` function to let `sys.path` modifications persist accross blocks. PR [#82](https://github.com/smarie/mkdocs-gallery/pull/82) by [Louis-Pujol](https://github.com/Louis-Pujol).
	- `sys.path` modifications now persist accross blocks of an example. `sys.path` is still reset after each example. PR [#82](https://github.com/smarie/mkdocs-gallery/pull/82) by [Louis-Pujol](https://github.com/Louis-Pujol).

[Louis-Pujol]

Thank you for pointing this out. I did the resetting of sys.path with a copy.deepcopy() + merge the last changes.

[smarie]

Perfect @Louis-Pujol ! Thanks a lot. Will this this now. Two releases on the same day :D