Writing the conf atomically to allow use in parallel environments.

[JulienPalard]

It may be just tightly related to my usage: I run HackInScience unit test in parallel because ... it's 16× faster to run them in parallel on my machine.

But each test use friendly, and having 16 friendly in parallel mess with the config file, rendering it unparsable, leading to my tests failing.

A good way to show the issue out of friendly:

from multiprocessing import Pool

def f(x):
    with open("testfile.txt", "w") as fd:
        for i in range(10):
            fd.write(str(x))
            fd.write("\n")

with Pool(16) as p:
    p.map(f, range(150))

leading to things like:

86
86
86
86
86
86
86
86
86
86
6
146
146

Without the patch my test are failing like 9 times every 10. With the path I haven't seen them fail (tried ~10 times)

[sourcery-ai[bot]]

Sourcery Code Quality Report

✅  Merging this PR will increase code quality in the affected files by 0.79%.

Quality metrics	Before	After	Change
Complexity	4.89 ⭐	4.67 ⭐	-0.22 👍
Method Length	56.12 ⭐	51.22 ⭐	-4.90 👍
Working memory	6.58 🙂	6.67 🙂	0.09 👎
Quality	76.18% ⭐	76.97% ⭐	0.79% 👍

Other metrics	Before	After	Change
Lines	125	134	9

Changed files	Quality Before	Quality After	Quality Change
friendly/settings.py	76.18% ⭐	76.97% ⭐	0.79% 👍

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File	Function	Complexity	Length	Working Memory	Quality	Recommendation

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[aroberge]

Thank you for this contribution, as it might be useful for people who, like you, are working in environments that use friendly in parallel sessions.

However, ... Do you have any reason to use friendly instead of friendly-traceback? Since you do your own formatting of the information with HackInScience, you should only need to use friendly-traceback. friendly is now "just" a fancy formatter which pulls the information from friendly-traceback, like HackInScience does, and uses its own method and various heavy dependencies such as Rich and pygments, to do some formatting.

In addition, friendly-traceback does not save settings like friendly does, and you would never have noticed this problem [and provided a nice solution for me ;-) ] if you would have use friendly-traceback instead.

[JulienPalard]

I'm using friendly-traceback 99% of the time, but sometimes instead of running a student function I run a whole student script (for exericses like my-add or calculator1), like this:

correction_helper.py-    try:
correction_helper.py-        proc = subprocess.run(
correction_helper.py-            [
correction_helper.py-                "python3",
correction_helper.py-                "-m",
correction_helper.py:                "friendly",
correction_helper.py-                "--formatter",
correction_helper.py:                "correction_helper.friendly_traceback_markdown",
correction_helper.py-                file,
correction_helper.py-                *args,
correction_helper.py-            ],
correction_helper.py-            stdout=subprocess.PIPE,
correction_helper.py-            stderr=subprocess.PIPE,

Am I using your libs right? Or do you see a better way?

[aroberge]

You should be able to replace "friendly" by "friendly_traceback" and it should work. I only have unit tests for friendly_traceback and I do have a test (that you initially wrote, I believe) for users of custom formatters.

[aroberge]

I will have to revert this pull request as it raises an exception when I run locally:

FileExistsError: [WinError 183] Cannot create a file when that file already exists: 'C:\\Users\\Andre\\AppData\\Local\\FriendlyTraceback\\tmpy2l_iv9z' -> 'C:\\Users\\Andre\\AppData\\Local\\FriendlyTraceback\\friendly.ini'

friendly_traceback does not save settings file (friendly.ini) and can be used from the command line instead of friendly.