For Python 3.13: A drop-in replacement for imghdr.what()

[cclauss]

The Python 3.13 release notes mention python-magic as one of the alternatives for imghdr which was removed from the Standard Library.

Given the discussion in #317, it might be quite helpful to have a drop-in replacement for imghdr.what(). It would provide a smooth transition to Py3.13 if developers could confidently replace all instances of imghdr.what() with magic.what() -- same args, same results.

• Travis CI: Test on Python 3.13 beta #317

---

Current pytest results: 45 passed in 0.05s

• test_what_from_file is 2 tests
• ztest_what_from_file_none is 0 test -- disabled with the leading z
• test_what_from_string is 10 tests
• test_what_from_string_py311 is 2 tests
  • Fail on imghdr only on Python < 3.11
• test_what_from_string_todo is 31 tests -- Lots of work to do!
  • Fail on magic

def what(file: PathLike | str | None, h: bytes | None) -> str:
    """A drop-in replacement for `imghdr.what()` which was removed from the standard
    library in Python 3.13."""

Usage:

# Replace...
from imghdr import what
# with...
from magic import what

# Or replace...
import imghdr
ext = imghdr.what(...)
# with...
import magic
ext = magic.what(...)

imghdr documentation: https://docs.python.org/3.12/library/imghdr.html
imghdr source code: https://github.com/python/cpython/blob/3.12/Lib/imghdr.py

[ddelange]

setup.py currently allows python 2.7 and 3.5+, where this will fail I think

[cclauss]

Python 2 died 1,603 days ago on 1/1/2020. Continuing to support it these daze only slows development.

It is probably high time to say that for Python 2.7 v0.4.27 is the last release.

Given that the GitHub Actions only test supported versions of Python how do we prove that legacy Python still works?

https://packaging.python.org/en/latest/discussions/setup-py-deprecated

[cclauss]

Closing in favor of puremagic.what() because it has better recognition of image file formats.