Refactor the MIMEAudio module

[JosephSBoyle]

We can remove almost half of this file without losing any expressiveness and marginally improve performance at the same time.

Linked PRs

• gh-102542 Refactor the mime audio module #102540
• gh-102542 Remove unused bytes object and bytes slicing #106433

[warsaw]

@JosephSBoyle - thanks for your contributions. I'm commenting here rather than on the PR (although I did add some feedback over there). Please also notice that Lib/email/mime/image.py uses a similar "rules" based mechanism to infer the image/* subtype when not provided.

One reason I went with this in my rewrite was so that we could easily extend the list of subtypes that we could recognize. Just add another @rule and you're done. While rule() isn't explicitly exposed publicly in either module, one could conceivably extend the list of subtypes in 3rd party code by doing something like:

from email.mime.audio import rule

@rule
def _my_image_type(h):
    if h[:5] == 'FLUFL':
        return 'flufl'

I wouldn't want to lose that implicit extensibility unless there's a good reason to. I'm not sure module size or "marginally improved performance" are compelling enough. Can you provide some performance numbers? Even if they were mind-blowingly better, I'm not sure this is performance critical code.

[JosephSBoyle]

Hi @warsaw, thanks for taking a look at the PR.

I wouldn't want to lose that implicit extensibility unless there's a good reason to

Fair enough, I'm sure that someone is registering their own rules so it makes sense to keep that functionality 😄

---

Would you accept a new, smaller PR to remove the unnecessary header slicing and unused fakefile instance?

[warsaw]

Would you accept a new, smaller PR to remove the unnecessary header slicing and unused fakefile instance?

I would! Yeah, there's no reason any more to slice the data and it makes sense for audio.py and image.py to have a similar implementation (but not the same implementation because they have different _rules).

[JosephSBoyle]

Awesome, I've created the new PR here: #106433.

@warsaw

[JosephSBoyle]

Closing as completed.