Allow multiple separators in Stream.readuntil

[bmerry]

BPO	37141
Nosy	@asvetlov, @1st1, @bmerry, @websurfer5
PRs	gh-81322: support multiple separators in Stream.readuntil #16429

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2019-06-03.09:32:30.680>
labels = ['type-feature', '3.9', 'expert-asyncio']
title = 'Allow multiple separators in Stream.readuntil'
updated_at = <Date 2019-09-26.19:48:53.882>
user = 'https://github.com/bmerry'

bugs.python.org fields:

activity = <Date 2019-09-26.19:48:53.882>
actor = 'yselivanov'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['asyncio']
creation = <Date 2019-06-03.09:32:30.680>
creator = 'bmerry'
dependencies = []
files = []
hgrepos = []
issue_num = 37141
keywords = ['patch']
message_count = 11.0
messages = ['344397', '344398', '344399', '344403', '344404', '344405', '344409', '352089', '352179', '353323', '353335']
nosy_count = 4.0
nosy_names = ['asvetlov', 'yselivanov', 'bmerry', 'Jeffrey.Kintscher']
pr_nums = ['16429']
priority = 'normal'
resolution = 'later'
stage = 'patch review'
status = 'pending'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue37141'
versions = ['Python 3.9']

[bmerry]

Text-based protocols sometimes allow a choice of newline separator - I work with one that allows either \r or \n. Unfortunately that doesn't work with StreamReader.readuntil, which only accepts a single separator, so I've had to do some hacky things to obtain lines without having to

From discussion in bpo-32052, it sounded like extending StreamReader.readuntil to support a tuple of separators would be feasible.

[asvetlov]

Would you make a PR?
I guess to modify Stream.readuntil()
StreamReader is deprecated, I'm not sure if we should add new functionality to this class.

[bmerry]

I wasn't aware of that deprecation - it doesn't seem to be mentioned at https://docs.python.org/3.8/library/asyncio-stream.html. What is the replacement?

[asvetlov]

Docs will be updated soon.
The change has landed a week ago, I had no time for docs update before 3.8 beta. Sorry for that.

The idea is: StreamReader and StreamWriter are merged into just Stream, open_connection() is replaced with connect() etc.

[bmerry]

Ok. Does the new Stream still have a similar interface for readuntil i.e. is this still a relevant request against the new API? I'm happy to let deprecated APIs stay as-is.

[asvetlov]

Yes, Stream supports all StreamReader and StreamWriter methods

[bmerry]

Ok, I've changed the issue title to refer to Stream. Since this would be a new feature, I assume it's off the table for 3.8, but I'll see if I get time to implement a PR in time for 3.9 (and get someone at work to sign off on the contributor agreement, which might be the harder part).

Thanks for the quick and helpful responses.

[bmerry]

I finally have permission from my employer to sign the contributors agreement, so I'll take a stab at this when I have some free time (unless nobody else gets to it first).

[asvetlov]

please do