Support Python 3.12 & 3.13 - was "imghdr module not found"

[Mukei]

After installing python-pptx and cloning the directory, I tried running my first markdown file conversion. Unfortunately, I ran into the below error.

Input

python3 -m md2pptx ./Downloads/output.pptx < ./Downloads/202404301018\ -\ Test.md

Output

Traceback (most recent call last):
  File "<frozen runpy>", line 198, in _run_module_as_main
  File "<frozen runpy>", line 88, in _run_code
  File "/Users/XX/Prog/01-Projects/md2pptx/md2pptx.py", line 28, in <module>
    import imghdr, struct
ModuleNotFoundError: No module named 'imghdr'

Did I miss any steps?

I am using python 3.13, on OSX 14.3 (23D56).

[Mukei]

I found out that in Python 3.13 imghdr was removed.

Important deprecations, removals or restrictions: PEP 594: The remaining 19 “dead batteries” have been removed from the standard library: aifc, audioop, cgi, cgitb, chunk, crypt, imghdr, mailcap, msilib, nis, nntplib, ossaudiodev, pipes, sndhdr, spwd, sunau, telnetlib, uu and xdrlib.

And PEP 594 gives the below advice:

imghdr: use the projects filetype, puremagic, or python-magic instead. (Contributed by Victor Stinner in gh-104773.)

I will switch to Python 3.12, but you might want to update the library to support future version of Python!

Thank you!

[MartinPacker]

Hi @Mukei. First, thank you for your bug report. I take currency seriously - but haven't seen benefits in 3.12 or 3.13 for this project. Nevertheless it needs to run.

I discovered an issue with 3.12 - which I aim to get a fix out for soon. Another deprecated behaviour going away, of course.

I actually had trouble getting a 3.12 install to find python-pptx - but obviously I need to fix that.

What I think the current use of imghdr is to recognise the dimensions (really proportions) of an image and its type. I'll have to see how I can replicate that function - preferably not creating another dependency (that might go away).

Anyhow, please do test on 3.12. I think you'll find it breaks there, too.

[MartinPacker]

It looks like Pillow at a high enough level could do. (9.5.0 for 3.12?) We already make it an optional prereq. Probably have to make it a mandatory one.

[MartinPacker]

I was wrong. imghdr is apparently just picking up the filetype for a graphic. Will have to think about how to do that differently. (Pillow is used for something else and can remain optional.)

[MartinPacker]

This Stack Overflow article poses the idea that one could use the file extension:

filename.lower().endswith(('.png', '.jpg', '.jpeg', '.tiff', '.bmp', '.gif'))

I'm not wowed by this but maybe imghdr was doing little more than that.

[MartinPacker]

Built not using imghdr but testing filename extensions. Please try the latest md2pptx file out. On 3.12 if you like. Or maybe 3.13. Let me know how it goes. I want to publish a release that says it supports 3.12.

[MartinPacker]

My initial tests with 3.12.2 and 3.13.0a5 show md2pptx continuing to work. (Installed both via pyenv and installed python-pptx into each environment.)

Thanks to your opening this issue @Mukei I now know how to test with newer versions. That should help keep this (and mdpre) current. mdpre is part of my make-driven presentation build toolchain and it worked fine with 3.12 and 3.13.

[MartinPacker]

Fixed and shipped in v4.4.

Closing. Please reopen if you don't consider it fixed.