IDLE: Fix tab completion after settings and some keys

[terryjreedy]

BPO	43654
Nosy	@gvanrossum, @rhettinger, @terryjreedy, @taleinat, @tetelevm
PRs	gh-87820: IDLE: fix config disabling tab completion #26403 gh-87820: IDLE: fix config disabling tab completion #26421

^{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 = 'https://github.com/terryjreedy'
closed_at = None
created_at = <Date 2021-03-29.08:40:35.880>
labels = ['expert-IDLE', 'type-bug', '3.9', '3.10', '3.11']
title = 'IDLE: Fix tab completion after settings and some keys'
updated_at = <Date 2022-01-20.19:56:17.994>
user = 'https://github.com/terryjreedy'

bugs.python.org fields:

activity = <Date 2022-01-20.19:56:17.994>
actor = 'taleinat'
assignee = 'terry.reedy'
closed = False
closed_date = None
closer = None
components = ['IDLE']
creation = <Date 2021-03-29.08:40:35.880>
creator = 'terry.reedy'
dependencies = []
files = []
hgrepos = []
issue_num = 43654
keywords = ['patch']
message_count = 13.0
messages = ['389673', '389791', '390731', '390732', '390755', '390824', '394542', '394545', '394631', '394883', '395063', '395201', '411043']
nosy_count = 5.0
nosy_names = ['gvanrossum', 'rhettinger', 'terry.reedy', 'taleinat', 'tetelevm']
pr_nums = ['26403', '26421']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue43654'
versions = ['Python 3.9', 'Python 3.10', 'Python 3.11']

[terryjreedy]

(Original report by Mikhail on bpo-43647, running 3.9 on Linux; verified and extended by me running 3.10 on Windows.)

Normally, "i<tab>" brings up a completion window with 'id', 'if', 'import', etc. Opening a Settings windows with Options => Configure IDLE and closing with Apply and Cancel or OK (which also applies) disables tab completion. Other completions (forced with ^<space> or auto with '.' or '/' and waits seem not affected. The only way to restore is to close and reopen each window.

Tab completions are enabled in editor.py with these two lines.
text.event_add('<<autocomplete>>', '<Key-Tab>')
text.bind("<<autocomplete>>", autocomplete.autocomplete_event)
Attribute and path completions, not affected, are enabled with these.
text.event_add('<<try-open-completions>>', '<KeyRelease-period>',
'<KeyRelease-slash>', '<KeyRelease-backslash>
text.bind("<<try-open-completions>>",
autocomplete.try_open_completions_event)
Similarly for some other things.

In configdialog, the relevant method is (179) def apply, who relevant calls are (219) deactivate_current_config and (230) activate_current_config. The former removes key bindings and the latter rebinds and makes other changes.

What is different about Tab versus '.' is that is tab also used for indents and the indent space is reset by 'activate...'. I will later add some debug prints to console based on the clues above.

[terryjreedy]

Investigation of this issue is complicated by the fact that the editor test widgets are wrapped by multicall.MulticallCreator. It intercepts bind and event method calls (other than event_generate) for user pseudoevents. It keeps its own map of pseudoevent names to handler and key sequences instead of passing the information on to tk.

The custom entry for "<<autocomplete>>" is the same,
[<bound method AutoComplete.autocomplete_event of <idlelib.autocomplete.AutoComplete object at 0x00000209DA4FBD20>>, [(0, 0, 'Tab')]]
both before deactivate_... and after activate_... .

I determined this by adding calls like the following
print('ei5 ', instance.text.event_info('<<autocomplete>>'))
and adding the following to the event_info(virtual) override.
print('mei', virtual, self.__eventinfo.get(virtual))

I will next look at the custom binding data that should map keys to event handlers.

[tetelevm]

Hello again!
I found another kind of bug, where the autosupplement window doesn't show up.
In order for the bug to occur, you need to put a non-string value into locals().
Example:

locals()['arg'] = 123  # or locals().setdefault('arg', 123)
# ^ it's okay

locals()[123] = 123  # or locals().setdefault(123, 123)
# ^ completion window is not shown

Of course, I know that "Whether or not updates to this dictionary will affect name lookups in the local scope and vice-versa not covered by any backwards compatibility guarantees" , but take a little bug :)

Here is the traceback of the error

Exception in Tkinter callback
Traceback (most recent call last):
  File "/usr/lib/python3.9/tkinter/__init__.py", line 1885, in __call__
    return self.func(*args)
  File "/usr/lib/python3.9/idlelib/multicall.py", line 176, in handler
    r = l[i](event)
  File "/usr/lib/python3.9/idlelib/autocomplete.py", line 74, in autocomplete_event
    opened = self.open_completions(TAB)
  File "/usr/lib/python3.9/idlelib/autocomplete.py", line 146, in open_completions
    comp_lists = self.fetch_completions(comp_what, mode)
  File "/usr/lib/python3.9/idlelib/autocomplete.py", line 171, in fetch_completions
    return rpcclt.remotecall("exec", "get_the_completion_list",
  File "/usr/lib/python3.9/idlelib/rpc.py", line 219, in remotecall
    return self.asyncreturn(seq)
  File "/usr/lib/python3.9/idlelib/rpc.py", line 250, in asyncreturn
    return self.decoderesponse(response)
  File "/usr/lib/python3.9/idlelib/rpc.py", line 270, in decoderesponse
    raise what
TypeError: '<' not supported between instances of 'int' and 'str'