IDLE: Dedenting with Shift+Tab

[kamek]

BPO	694339
Nosy	@rhettinger, @terryjreedy, @kbkaiser, @serwy, @rovitotv, @mlouielu, @csabella
PRs	gh-38066: IDLE: Dedenting with shift+tab #2210
Files	common_dedent.diff

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

Show more details

GitHub fields:

assignee = 'https://github.com/terryjreedy'
closed_at = None
created_at = <Date 2003-02-27.13:08:54.000>
labels = ['expert-IDLE', 'type-feature']
title = 'IDLE: Dedenting with Shift+Tab'
updated_at = <Date 2017-09-28.06:59:47.992>
user = 'https://bugs.python.org/kamek'

bugs.python.org fields:

activity = <Date 2017-09-28.06:59:47.992>
actor = 'taleinat'
assignee = 'terry.reedy'
closed = False
closed_date = None
closer = None
components = ['IDLE']
creation = <Date 2003-02-27.13:08:54.000>
creator = 'kamek'
dependencies = []
files = ['13457']
hgrepos = []
issue_num = 694339
keywords = ['patch']
message_count = 12.0
messages = ['53784', '53785', '53786', '53787', '53788', '84392', '150059', '212906', '220193', '220197', '296074', '296139']
nosy_count = 11.0
nosy_names = ['rhettinger', 'terry.reedy', 'kbk', 'kamek', 'gpolo', 'roger.serwy', 'THRlWiTi', 'Todd.Rovito', 'Sean.Wolfe', 'louielu', 'cheryl.sabella']
pr_nums = ['2210']
priority = 'normal'
resolution = None
stage = 'test needed'
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue694339'
versions = ['Python 3.6']

[kamek]

IDLE already provides quick block indenting, by
selecting one or more lines and pressing Tab. So, it
would make sense to have Shift+Tab to do the opposite
work. While there's already Alt+[ (and Alt+] to indent),
Shift+Tab is more intuitive, especially to those who are
used to other Windows developer tools, like Visual
Studio or TextPad.

[rhettinger]

Logged In: YES
user_id=80475

While you get used to it quickly, I've bumped in to this also.
It is nice to have the control keys work the same across
applications.

[kamek]

Logged In: YES
user_id=539453

This can be considered solved in the newest IDLE versions,
as you can set custom shortcuts.

[rhettinger]

Logged In: YES
user_id=80475

Evenso, it may be better to have it work right out of the box.

[kbkaiser]

Logged In: YES
user_id=149084

What I'd really like is smart tabs like python-mode, where a tab
(re)indents the line to the correct point based on the syntax,
and a backspace backs up to the previous level.

Since IDLE already knows how to indent I'm hoping that that
won't be to difficult to implement.

[gpolo]

Patch added for allowing, and defining, Shift-Tab as the default binding
for dedenting.

The problem is that dedent-region may do more than one would expect.

[serwy]

I applied the patch and encountered a problem. MultiCall.py is replacing "<Shift-Key-Tab>" with "<Shift-KeyPress-Tab>". When this happens, the logic for rebinding "<<PrevWindow>>" fails.

event_info('<<PrevWindow>>') returns ('<Key-ISO_Left_Tab>', '<Key-hpBackTab>', '<Shift-Key-Tab>')

event_info('<<dedent-region>>') returns ('<Control-KeyPress-bracketleft>', '<Shift-KeyPress-Tab>')

This is with 3.3a0 on Ubuntu 11.04.

[SeanWolfe]

I did a couple tests and the shift-tab and tab work pretty much as expected. There's a small quirk for a single-line edit:

• place cursor on beginning of line
• tab forward
  --> the text indents as expected
• shift-tab
  --> the entire line is highlighted
  --> the cursor now appears beneath the line
  --> subsequent typing however affects the highlighted line

For the single-line case, it would be cleaner to have it stay on the same line without highlighting.

This is OSX 10.9, python 2.7.6+ and 3.4.rc1+

[taleinat]

Regarding Roger Serwy's comment, we could either:

1. normalize the event descriptions using MultiCall's _parse_sequence() and _triplet_to_sequence() functions
2. remove any Shift-Tab bindings from <<PrevWindow>>

I suggest #2.

Regarding the patch itself:

1. Was the existing default binding of Ctrl-[ removed on purpose in Lib/idlelib/configHandler.py? According to the same patch, in the config files it is still there along-side the new Shift-Tab binding. At the least, these should be consistent.

2. In the code re-binding the <<Prev-Window>> event in EditorWindow.py, shouldn't there be a "break" at the end of the "if" clause inside the "for" loop?

[terryjreedy]

The fact that Tab indents regions as well as lines seems not be documented. This should be added to Automatic Indentation (which should just be Indentation) with BackTab doc addition if not sooner.

On Windows, 3.4.1, shift-tab is the same as tab. The same is true in Notepad (not a model to follow), but Notepad++ dedents. Doing the same in Idle, within the editor, seems like a reasonable request.

The unplanned and strange OSX behavior should be fixed.

From the patch, I would gather that the problem is that tk hard-codes shift-Tab to <<prev-window (and, I would expect, tab to <<next-window>>). (This works but is currently useless in the dialogs.) If that is so, why do they currently act the same (for me) in the editor? Does tk automatically rebind Tab to indent-region in a text widget?

Tal: option 2 seems like something to try. If Shift-Tab is user configurable (and I think baked-in like Tab would be ok), then it should be *added* in both places. You might be right about break, except this is a moot point if the code is wrong.