Issue 18615: sndhdr.whathdr could return a namedtuple

Both sndhdr.whathdr an sndhdr.what returns a tuple with various information, while it could return a namedtuple. I attached a patched for this, with tests as well.

Ping, please review. I guess it is minimal enough to get into 3.4.

Ping. :)

Personally I doubt it is a good idea to convert any tuple to named tuple. There are downsides: this increases memory usage and decreases performance; this changes pickled data and makes it backward incompatible (and even worse with other serialization methods).

But it improves the API. It's much nicer to actually access the values returned by sndhdr as f.type, f.sampling_rate, f.channels than f[0], f[1], f[2]. You do have a point though. Would it be more acceptable if we'll provide a new function which returns a namedtuple and leaving `whathdr` and `what` in peace?

Serhiy, if there's no actual gain in changing this, should we close the issue?

This is a reasonable improvement.  It was what named tuples were intended to be used for.

If Raymond found this feature helpful, I have no strong objection.

Only several comments:

* A named tuple is documented as having fields: type, sampling_rate, channels, frames, bits_per_sample.

* User tests in existing code return tuples. what() and whathdr() should convert result to named tuple. Changing standard tests after this is redundant.

* If we guarantee pickleability, we will stick with nametuple's name. It is not more implementation detail which we can change in any moment, all future versions of Python should have sndhdr._SndHeaders. Is it good to use underscored name?

Thanks, Serhiy, for the review. Here's the updated version.

A namedtuple is still wrongly documented.

Here's a new version. It adds versionchanged directive for 'whathdr' and 'what'. Serhiy, I hope that now I got right the documentation of the return type. I didn't understand at first what was wrong.

The documentation says:

"""
When these functions are able to determine
what type of sound data is stored in a file,
they return a :func:`~collections.namedtuple`, containing five attributes:
(``type``, ``sampling_rate``, ``channels``,
``frames``, ``bits_per_sample``).
"""

But actual attributes of returned namedtuple are filetype, framerate, nchannels, nframes and sampwidth.

Thanks.

Serhiy, is there anything left to do for this patch?

The patch looks good.  I'll apply it shortly.

New changeset ef72142eb8a2 by R David Murray in branch 'default':
#18615: Make sndhdr return namedtuples.
https://hg.python.org/cpython/rev/ef72142eb8a2

Committed.  Thanks, Claudiu.

stage: commit review -> resolved

messages: + msg224951

messages: + msg223147

messages: + msg223131

messages: + msg223092
nosy: + rhettinger

stage: patch review