Tools/demo/redemo.py broken

[csarn]

BPO	30722
Nosy	@ezio-melotti, @berkerpeksag, @serhiy-storchaka, @mlouielu, @csarn
PRs	bpo-30722: adjust to new RegexFlags enum, remove LOCALE checkbox #2311 [3.6] bpo-30722: Make redemo work with Python 3.6+ (GH-2311) #4090 bpo-30722: Fix NEWS entries #8501 [3.7] bpo-30722: Fix NEWS entries (GH-8501) #8503 [3.6] bpo-30722: Fix NEWS entry (GH-8501) #8504

^{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 = <Date 2018-07-27.16:18:23.283>
created_at = <Date 2017-06-21.08:57:43.914>
labels = ['type-bug', '3.7']
title = 'Tools/demo/redemo.py broken'
updated_at = <Date 2018-07-27.16:18:23.282>
user = 'https://github.com/csarn'

bugs.python.org fields:

activity = <Date 2018-07-27.16:18:23.282>
actor = 'berker.peksag'
assignee = 'none'
closed = True
closed_date = <Date 2018-07-27.16:18:23.283>
closer = 'berker.peksag'
components = ['Demos and Tools']
creation = <Date 2017-06-21.08:57:43.914>
creator = 'Christoph Sarnowski2'
dependencies = []
files = []
hgrepos = []
issue_num = 30722
keywords = ['patch']
message_count = 13.0
messages = ['296530', '296532', '296533', '296535', '296543', '296547', '304825', '304827', '304828', '309024', '322503', '322504', '322506']
nosy_count = 6.0
nosy_names = ['ezio.melotti', 'mrabarnett', 'berker.peksag', 'serhiy.storchaka', 'louielu', 'Christoph Sarnowski2']
pr_nums = ['2311', '4090', '8501', '8503', '8504']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue30722'
versions = ['Python 3.6', 'Python 3.7']

[csarn]

In Python 3.6, the flags in the "re" module became members of an enum.IntFlag, whereas before they were just ints.

This breaks the regex demo in Tools/demo/redemo.py.

To fix this, in line 86 of redemo.py,

 getattr(re, name)

has to be replaced by

getattr(re, name).value

Also, the checkbox for "LOCALE" can be removed (or fixed), as re.LOCALE is invalid for str patterns.

[mlouielu]

Hi Christoph, chould you provide a small example that breaks the regex demo? thanks!

[mlouielu]

Also, would you like to contribute with PR on GitHub?

[csarn]

Hi, sorry for forgetting steps to reproduce the bug.

Easiest way to see it is to start redemo.py from a console (important on windows), so you can see stdout/stderr.
Then just a click on any of those flag checkboxes leads to an exception backtrace printed on the console.

And to demonstrate that the flag checkbox does not work, enter ".*" (without quotes) as the pattern, and any multiline string as the string to search, and activate the checkbox "MULTILINE".
Correct behaviour: no exception, all lines of the string get highlighted as the first match
Erroneous (actual) behaviour: An exception traceback gets printed: '_tkinter.TclError: expected integer but got "RegexFlag.MULTILINE"'
and only the first line is highlighted as first match, demonstrating that the MULTILINE flag is in fact not active.

When it comes to a pull request, I could do that for the change that I proposed. But regarding the "LOCALE" flag, the better solution (in my opinion) would be to make it work instead of just removing it, but that is a more elaborate change that I am not able to spend time on.

What would you suggest?
a) I provide a pull request, leaving "LOCALE" flag behaviour broken
b) I provide a pull request, removing "LOCALE" flag (to be introduced again when someone is willing to fix it)

[serhiy-storchaka]

I think ideally it would be nice to provide a switch between Unicode and bytes and disable the LOCALE flag in the Unicode mode. But this is too complex task. I think it is better to remove LOCALE.

[csarn]

By the way, I confused the flags, in my error-reproduction steps, instead of the re.MULTILINE flag, it is the re.DOTALL flag that should lead to all lines being matched by ".*".

[berkerpeksag]

New changeset 62adc55 by Berker Peksag (Christoph Sarnowski) in branch 'master':
bpo-30722: Make redemo work with Python 3.6+ (GH-2311)
62adc55

[berkerpeksag]

New changeset a5f9d24 by Berker Peksag (Miss Islington (bot)) in branch '3.6':
bpo-30722: Make redemo work with Python 3.6+ (GH-2311)
a5f9d24

[berkerpeksag]

Thank you, Christoph. I wasn't aware of Tools/demo/redemo.py and I must say it was fun to play with while reviewing PR 2311.

[serhiy-storchaka]

The news message is verbose but looks misleading to me. There is nothing invalid with usages like getattr(re, 'DOTALL'). It is the same as re.DOTALL, and using enums haven't changed this.