[issue38673] REPL shows continuation prompt (...) when comment or space entered

[Guido van Rossum]

Guido van Rossum  added the comment:

(And I'm giving up on 3.6 and 2.7 as these are close to their end of life.)

--

___
Python tracker 

___
___
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue38673] REPL shows continuation prompt (...) when comment or space entered

[Guido van Rossum]

Change by Guido van Rossum :


--
resolution:  -> fixed
stage: patch review -> resolved
status: open -> closed

___
Python tracker 

___
___
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue38673] REPL shows continuation prompt (...) when comment or space entered

[Guido van Rossum]

Guido van Rossum  added the comment:

Ned agreed, it's merged into 3.7, so let's close.

--

___
Python tracker 

___
___
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue38673] REPL shows continuation prompt (...) when comment or space entered

[Ned Deily]

Ned Deily  added the comment:


New changeset 188d5ae6f047342f3d6860646ccf1a523ef8b0ed by Ned Deily (Miss 
Islington (bot)) in branch '3.7':
bpo-38673: dont switch to ps2 if the line starts with comment or whitespace 
(GH-17421) (GH-17522)
https://github.com/python/cpython/commit/188d5ae6f047342f3d6860646ccf1a523ef8b0ed


--
nosy: +ned.deily

___
Python tracker 

___
___
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue38673] REPL shows continuation prompt (...) when comment or space entered

[miss-islington]

Change by miss-islington :


--
pull_requests: +17000
pull_request: https://github.com/python/cpython/pull/17522

___
Python tracker 

___
___
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue38673] REPL shows continuation prompt (...) when comment or space entered

[Terry J. Reedy]

Terry J. Reedy  added the comment:

I would prefer that.  I think treating '\n' and ' \n' differently is a bit of a 
bug.  And the fix pretty well matches code/codeop behavior.  I have so far not 
imagined how it could break code.But you could let Ned Deily decide, before 
the next rc, if you want.

I am neutral on 2.7.

--
versions:  -Python 3.5, Python 3.6

___
Python tracker 

___
___
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue38673] REPL shows continuation prompt (...) when comment or space entered

[Guido van Rossum]

Guido van Rossum  added the comment:

So 3.8.1 got backported by Miss Islington. Do we want this in earlier releases?

--

___
Python tracker 

___
___
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue38673] REPL shows continuation prompt (...) when comment or space entered

[miss-islington]

miss-islington  added the comment:


New changeset 184a3812b81e2f7d4bc6453bf7ceabe8ac590202 by Miss Islington (bot) 
in branch '3.8':
bpo-38673: dont switch to ps2 if the line starts with comment or whitespace 
(GH-17421)
https://github.com/python/cpython/commit/184a3812b81e2f7d4bc6453bf7ceabe8ac590202


--

___
Python tracker 

___
___
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue38673] REPL shows continuation prompt (...) when comment or space entered

[miss-islington]

Change by miss-islington :


--
pull_requests: +16993
pull_request: https://github.com/python/cpython/pull/17516

___
Python tracker 

___
___
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue38673] REPL shows continuation prompt (...) when comment or space entered

[Guido van Rossum]

Guido van Rossum  added the comment:

I'd like to backport this to 3.8.1 at least. Are people interested in getting 
it backported to earlier versions?

--

___
Python tracker 

___
___
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue38673] REPL shows continuation prompt (...) when comment or space entered

[miss-islington]

miss-islington  added the comment:


New changeset 109fc2792a490ee5cd8a423e17d415fbdedec5c8 by Miss Islington (bot) 
(Batuhan Taşkaya) in branch 'master':
bpo-38673: dont switch to ps2 if the line starts with comment or whitespace 
(GH-17421)
https://github.com/python/cpython/commit/109fc2792a490ee5cd8a423e17d415fbdedec5c8


--
nosy: +miss-islington

___
Python tracker 

___
___
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue38673] REPL shows continuation prompt (...) when comment or space entered

[Batuhan]

Change by Batuhan :


--
keywords: +patch
pull_requests: +16902
stage:  -> patch review
pull_request: https://github.com/python/cpython/pull/17421

___
Python tracker 

___
___
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue38673] REPL shows continuation prompt (...) when comment or space entered

[Guido van Rossum]

Guido van Rossum  added the comment:

> But is the 'fix' in _maybe_compile at all applicable to the REPL?  Or might a 
> parser change REPL fix make the code in _maybe_compile unneeded?

I don't know.  Most of the contortions in code.py codeop.py are meant to 
emulate what the parser does without help in the REPL: keep asking for input 
until one of the following happens:

- a syntax error is found;

- a simple statement is parsed till completion;

- an empty line is found at a point where a compound statement is potentially 
complete.

The bug here is that apparently the above conditions aren't quite enough, and 
it seems we need to add:

- a line that contains just whitespace and/or a comment is seen before anything 
else.

The reason that IDLE has to reimplement similar logic is that the parser 
(actually, the tokenizer) isn't written as a coroutine to which you send lines 
you read -- it's written as a blocking function that you pass a file and the 
function will attempt to read lines from the file.  The function returns a 
parse tree or raise an error.  That model doesn't work in IDLE, which needs to 
stay reactive while the shell window is in the middle of a statement.

I think we'll find that the bug is *very* old.  IIRC the initial releases of 
Python didn't have the rule that indentation is ignored between matching 
parentheses/brackets/braces.  In those days the tokenizer also didn't 
gracefully skip blank lines, or lines with comments that weren't aligned with 
the current indentation level.  So then checking for empty lines was good 
enough.

--

___
Python tracker 

___
___
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue38673] REPL shows continuation prompt (...) when comment or space entered

[Terry J. Reedy]

Terry J. Reedy  added the comment:

Fix corner case bugs in IDLE would definitely be a separate issue.  But is the 
'fix' in _maybe_compile at all applicable to the REPL?  Or might a parser 
change REPL fix make the code in _maybe_compile unneeded?

--

___
Python tracker 

___
___
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue38673] REPL shows continuation prompt (...) when comment or space entered

[Guido van Rossum]

Guido van Rossum  added the comment:

Regarding the IDLE mystery, *if* there's a difference between how it treats " # 
a" and "# a", this must be due to some part of the code that's invoked before 
_maybe_compile() is called, right?

But that's immaterial to this bug -- I'm only complaining about the "builtin" 
REPL.

--

___
Python tracker 

___
___
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue38673] REPL shows continuation prompt (...) when comment or space entered

[Terry J. Reedy]

Terry J. Reedy  added the comment:

Entering 'pass' or a completely blank line results in a new primary prompt, at 
least on Windows. The Windows REPL otherwise prints ... even for effectively 
blank lines.  IDLE usually prints a new prompt for effectively blank lines.

>>> 
>>> #a
>>> # a
>>>  #a
>>>

I agree that these look better.  This behavior comes from 
code.InteractiveInterpreter and ultimately codeop.

def _maybe_compile(compiler, source, filename, symbol):
# Check for source consisting of only blank lines and comments
for line in source.split("\n"):
line = line.strip()
if line and line[0] != '#':
break   # Leave it alone
else:
if symbol != "eval":
source = "pass" # Replace it with a 'pass' statement

As noted above, 'pass\n' is treated the same as '\n'

The first line above originally had a space, but IDLE appears to strip trailing 
whitespace also, even outside of comments.  (For an ending '\ ', this prevents 
SyntaxError, but maybe this is a bad lesson for beginners.)  However, I did 
find a case with an unnecessary continuation line.

>>>  # a
 
>>> 

This puzzles me, as it should be treated exactly the same as without the space 
after '#'.  ast.dump(ast.parse(' # a\n', '', 'single')) gives the same result, 
'Module(body=[], type_ignores=[])', as without.

--
nosy: +terry.reedy

___
Python tracker 

___
___
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue38673] REPL shows continuation prompt (...) when comment or space entered

[Guido van Rossum]

Guido van Rossum  added the comment:

Yes, that's likely where the change should be made.

I think if the *first* token encountered is either NL or COMMENT the parse 
should be abandoned by the tokenizer.

--

___
Python tracker 

___
___
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue38673] REPL shows continuation prompt (...) when comment or space entered

[Anders Lorentsen]

Anders Lorentsen  added the comment:

As a person without much experience, it sounded like a simple enough task, but 
having dug a bit, I found it quite complicated. It seems to me that the 
interpreter loop (in the standard REPL, that you get when you start ./python, 
blocks for input somewhere inside a massive function called 'parsetok' (in 
Parser/parsetok.c). Now, I could maybe investigate further, to have it return 
to the interpreter loop if it reads a comment (or empty line), but I'm afraid 
to mess up something.

>From my understanding, there aren't that many other choices, because 
>parsetok() doesn't return before you finish the statement (in other words, it 
>does not return if you type a comment line or a blank line - it instead waits 
>for more input, as indicated by the '... ').

Am I way off in concluding that this would be a change to the parser?

--
nosy: +Phaqui

___
Python tracker 

___
___
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue38673] REPL shows continuation prompt (...) when comment or space entered

[Guido van Rossum]

New submission from Guido van Rossum :

This has always bothered me, and it shouldn't be necessary.

This session:

>>> #foo
... 
>>> 

should really have been

>>> #foo
>>>

It's confusing that the REPL prompt switches to "..." here, for no good reason. 
It should just treat the line as empty.

Ditto if you enter a space (there's an invisible space after the first prompt):

>>>  
... 
>>>

--
components: Interpreter Core
messages: 355903
nosy: gvanrossum
priority: low
severity: normal
status: open
title: REPL shows continuation prompt (...) when comment or space entered
versions: Python 2.7, Python 3.5, Python 3.6, Python 3.7, Python 3.8, Python 3.9

___
Python tracker 

___
___
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com