[issue5811] io.BufferedReader.peek(): Documentation differs from Implementation

Change by desbma : -- nosy: +desbma ___ Python tracker ___ ___ Python-bugs-list mailing list Unsubscribe:

[issue5811] io.BufferedReader.peek(): Documentation differs from Implementation

Martin Panter added the comment: The non-blocking behaviour that I documented in my patch is under question in Issue 13322. I think it would be nice change the implementation to either return None or raise BlockingIOError. -- ___ Python tracker

[issue5811] io.BufferedReader.peek(): Documentation differs from Implementation

Martin Panter added the comment: Here is a simple documentation patch to guarantee that at least one byte is normally returned. This would make the method much more useful, and compatible with the BZ2File and LZMAFile interfaces, allowing them to use BufferedReader, as I propose to do in

[issue5811] io.BufferedReader.peek(): Documentation differs from Implementation

Martin Panter added the comment: Is the current documentation as accurate as it can be? “The number of bytes returned may be less or more than requested” To me this has always made this method practically useless. A valid implementation could just always return b. I noticed the BZ2File.peek()

[issue5811] io.BufferedReader.peek(): Documentation differs from Implementation

Changes by Mark Lawrence breamore...@yahoo.co.uk: -- nosy: -BreamoreBoy ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue5811 ___ ___

[issue5811] io.BufferedReader.peek(): Documentation differs from Implementation

Mark Lawrence added the comment: Looks like this has slipped under the radar. I'll leave working on it to the experts :) -- nosy: +BreamoreBoy ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue5811

[issue5811] io.BufferedReader.peek(): Documentation differs from Implementation

Antoine Pitrou pit...@free.fr added the comment: I haven't read the patch in detail but I don't think you should have changed read1(). read1() is there for optimization purposes and its current behaviour makes sense IMO. -- versions: +Python 2.7 ___

[issue5811] io.BufferedReader.peek(): Documentation differs from Implementation

Nick Coghlan ncogh...@gmail.com added the comment: The doc revision definitely does a better job of characterising the current underspecified behaviour :) I agree with Antoine that at most a single read would be better wording. -- ___ Python tracker

[issue5811] io.BufferedReader.peek(): Documentation differs from Implementation

Lucas Prado Melo lukepada...@gmail.com added the comment: Ok A new patch without read1() changes. Only one test fails, a read1() test: == FAIL: test_read1 (test.test_io.PyBufferedRWPairTest)

[issue5811] io.BufferedReader.peek(): Documentation differs from Implementation

Benjamin Peterson benja...@python.org added the comment: I updated the documentation in r73429. Is that better? -- versions: +Python 3.2 -Python 3.0 ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue5811

[issue5811] io.BufferedReader.peek(): Documentation differs from Implementation

Antoine Pitrou pit...@free.fr added the comment: Rather than only a single read on the raw stream, it should be at most a single read on the raw stream, IMHO. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue5811

[issue5811] io.BufferedReader.peek(): Documentation differs from Implementation

Lucas Prado Melo lukepada...@gmail.com added the comment: Here is a patch that passes all the tests (I had to change some of them though, they were expecting erroneous behaviours IMHO). The biggest problem was the read1 testing, I've tried to get the maximum of bytes less than or equal to what

[issue5811] io.BufferedReader.peek(): Documentation differs from Implementation

Lucas Prado Melo lukepada...@gmail.com added the comment: Here, it's a patch that passes all the tests (I had to change some of them though, they were expecting erroneous behaviours IMHO). The biggest problem was the read1 testing, I've tried to get the maximum of bytes less than or equal to

[issue5811] io.BufferedReader.peek(): Documentation differs from Implementation

Antoine Pitrou pit...@free.fr added the comment: Lucas, it is indeed impossible for peek() to return more than the buffer size and remain compatible with non-seekable raw streams. That's why it /never/ returns more than the buffer size. As for the fact that peek() doesn't behave as documented,

[issue5811] io.BufferedReader.peek(): Documentation differs from Implementation

Lucas Prado Melo lukepada...@gmail.com added the comment: We could fill the buffer while moving its start point to 0. I guess this behavior would require a new function (or a new parameter to Modules/_io/bufferedio.c:_bufferedreader_fill_buffer() ). If you are ok with that I could write a patch.

[issue5811] io.BufferedReader.peek(): Documentation differs from Implementation

Antoine Pitrou pit...@free.fr added the comment: We could, however, enforce the passed argument and only return the whole remaining buffer when no argument is given. This is a bit like Frederick Reeve's proposal on python-dev, but less sophisticated and therefore less tedious to implement. In

[issue5811] io.BufferedReader.peek(): Documentation differs from Implementation

Antoine Pitrou pit...@free.fr added the comment: We could fill the buffer while moving its start point to 0. I guess this behavior would require a new function (or a new parameter to Modules/_io/bufferedio.c:_bufferedreader_fill_buffer() ). If you are ok with that I could write a patch. The

[issue5811] io.BufferedReader.peek(): Documentation differs from Implementation

Benjamin Peterson benja...@python.org added the comment: I'm downgrading this because it can't be changed until after 3.1 is released. -- assignee: benjamin.peterson - priority: release blocker - normal ___ Python tracker rep...@bugs.python.org

[issue5811] io.BufferedReader.peek(): Documentation differs from Implementation

Nick Coghlan ncogh...@gmail.com added the comment: It's not the docstring that is wrong for the current behaviour, it's the IO.BufferedReader documentation: peek([n]) Return 1 (or n if specified) bytes from a buffer without advancing the position. Only a single read on the raw stream is

[issue5811] io.BufferedReader.peek(): Documentation differs from Implementation

Nick Coghlan ncogh...@gmail.com added the comment: Assigned to Benjamin for assessment - this should be considered for rc2 since it's still broken in 3.1: f = open('setup.py', 'rb') len(f.peek(10)) 4096 len(f.peek(1)) 4096 len(f.peek(4095)) 4096 len(f.peek(10095)) 4096 Brought up on

[issue5811] io.BufferedReader.peek(): Documentation differs from Implementation

Benjamin Peterson benja...@python.org added the comment: I think the argument should be used as a upper bound; I will look at this tomorrow. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue5811

[issue5811] io.BufferedReader.peek(): Documentation differs from Implementation

Lucas Prado Melo lukepada...@gmail.com added the comment: Hey guys, I did a patch about this one. I didn't do many tests but I guess it is ok (it works like I think it should). What do you think? -- keywords: +patch nosy: +conf Added file: http://bugs.python.org/file14281/peek.diff

[issue5811] io.BufferedReader.peek(): Documentation differs from Implementation

Lucas Prado Melo lukepada...@gmail.com added the comment: Oops I overlooked I minor flaw. A second version. -- Added file: http://bugs.python.org/file14282/peek2.diff ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue5811

[issue5811] io.BufferedReader.peek(): Documentation differs from Implementation

Lucas Prado Melo lukepada...@gmail.com added the comment: There's a problem with my patch... When the size of the data we want to peek is too big ( buffer_len - start ) the cursor will move, thus there isn't a case where the peek function would work properly (except when we want to peek() just

[issue5811] io.BufferedReader.peek(): Documentation differs from Implementation

New submission from Torsten Rottmann tr...@meditec-gmbh.com: The documented behavior of io.BufferedReader.peek([n]) states: peek([n]) Return 1 (or n if specified) bytes from a buffer without advancing the position. Thereas the parameter n is the _max_ length of returned bytes. Implementation

[issue5811] io.BufferedReader.peek(): Documentation differs from Implementation

Torsten Rottmann tr...@meditec-gmbh.com added the comment: Note: this is also in Python 2.6 -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue5811 ___

[issue5811] io.BufferedReader.peek(): Documentation differs from Implementation

Torsten Rottmann tr...@meditec-gmbh.com added the comment: Proposed patch to fix this: set the default of n to 1 as stated by docs: def _peek_unlocked(self, n=1): return n bytes: return self._read_buf[self._read_pos:self._read_pos+n] -- ___