Issue 43337: export the set newline value on TextIOBase/TextIOWrapper

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This issue has been migrated to GitHub: https://github.com/python/cpython/issues/87503

classification

Title:	export the set newline value on TextIOBase/TextIOWrapper
Type:	enhancement	Stage:
Components:	IO	Versions:

process

Status:	open	Resolution:
Dependencies:		Superseder:
Assigned To:		Nosy List:	benjamin.peterson, calestyo
Priority:	normal	Keywords:

Created on 2021-02-27 05:45 by calestyo, last changed 2022-04-11 14:59 by admin.

Messages (1)
msg387767 - (view)	Author: Christoph Anton Mitterer (calestyo)	Date: 2021-02-27 05:45
Hey. It seems there is no way to determine the newline value (None, '', \n, \r, \r\n) of a given text stream. .newlines rather gives the newlines that have been encountered so far. Just like .encoding and .errors this would be quite useful for anything that gets a stream and operates on it, possibly needing to know which newlines it will see when reading from the stream. One example would be, after line = stream.readline(4096+n) one want's to know whether actually a full line of 4096 characters has been read. Putting aside newline="", for simplicity here, n already depends on whether newline was None, \n, \r or \r\n, as would any check like line.endswith(foo). Maybe some attribute, that indicates the most recently read newline in newline="" mode, would be helpful, too. Cheers, Chris.

msg387767 - (view)

Author: Christoph Anton Mitterer (calestyo)

Date: 2021-02-27 05:45

Hey.

It seems there is no way to determine the newline value (None, '', \n, \r, \r\n) of a given text stream.
.newlines rather gives the newlines that have been encountered so far.


Just like .encoding and .errors this would be quite useful for anything that gets a stream and operates on it, possibly needing to know which newlines it will see when reading from the stream.

One example would be, after line = stream.readline(4096+n) one want's to know whether actually a full line of 4096 characters has been read.
Putting aside newline="", for simplicity here, n already depends on whether newline was None, \n, \r or \r\n, as would any check like line.endswith(foo).


Maybe some attribute, that indicates the most recently read newline in newline="" mode, would be helpful, too.


Cheers,
Chris.

History
Date	User	Action	Args
2022-04-11 14:59:42	admin	set	github: 87503
2021-03-05 21:03:13	terry.reedy	set	nosy: + benjamin.peterson
2021-02-27 05:45:28	calestyo	create