tkinter.Text.count(index1, index2) returns None not (0,) when index1 equals index2 #97928

RogerMarsh · 2022-10-05T19:44:29Z

Surely the Text.count() method should return (0,) in the title code snippet? Following the example of what happens when more than one option is given.

I suppose the text_count method should do so too, but it was a hack of something that did not exist when written.

Tk8.6 documentation says a list of integers is returned.

Sample code below.

import tkinter


def text_count(widget, index1, index2, *options):
    """Hack Text count command. Return integer, or tuple if len(options) > 1.

    Tkinter does not provide a wrapper for the Tk Text widget count command
    at Python 2.7.1

    widget is a Tkinter Text widget.
    index1 and index2 are Indicies as specified in TkCmd documentation.
    options must be a tuple of zero or more option values.  If no options
    are given the Tk default option is used.  If less than two options are
    given an integer is returned.  Otherwise a tuple of integers is returned
    (in the order specified in TkCmd documentation).

    See text manual page in TkCmd documentation for valid option values and
    index specification.

    Example:
    chars, lines = text_count(widget, start, end, '-chars', '-lines')

    """
    return widget.tk.call((widget._w, 'count') + options + (index1, index2))


text = tkinter.Text()

print(text.count("1.0", tkinter.END))                                       # (1,0)
print(text.count("1.0", "1.0"))                                                 # None
print(text_count(text, "1.0", "1.0"))                                        # 0
print(text_count(text, "1.0", tkinter.END))                              # 1
print(text.count("1.0", tkinter.END, "chars"))                         # (1,)
print(text.count("1.0", "1.0", "chars"))                                   # None
print(text_count(text, "1.0", "1.0", "-chars"))                         # 0
print(text_count(text, "1.0", tkinter.END, "-chars"))               # 1
print(text.count(tkinter.END, "1.0", "chars"))                         # (-1,)
print(text_count(text, tkinter.END, "1.0", "-chars"))               # -1
print(text.count("1.0", tkinter.END, "chars", "lines"))             # (1, 1)
print(text.count("1.0", "1.0", "chars", "lines"))                       # (0, 0)
print(text_count(text, "1.0", "1.0", "-chars", "-lines"))            # (0, 0)
print(text_count(text, "1.0", tkinter.END, "-chars", "-lines"))  # (1, 1)

Linked PRs

serhiy-storchaka · 2022-10-14T13:45:10Z

There are other issues with Text.count().

Options starting with '-' are silently ignored. It can lead to bugs: text.count(begin, end, '-lines')) returns the the number of "indices" rather than the number of lines. Perhaps the initial intention was to only ignore the '-' prefix, so '-lines' and 'lines' would mean the same, but it never worked. It is better to make it an error.
If wantobjects was set to 0, the method returns a string.
It tries to always return a tuple (except when the result is zero count), but it fails with the 'update' option (which is undocumented in Tkinter). It returns an integer for 'update', 'ypixels' and 'update', 'indices', but a 1-tuple for 'ypixels' and 'update'.

There were no any tests for this method, so all this was unnoticed.

Other issues could be solved in compatible way, but the originally reported issue does not have backward compatible solution. Returning (0.) instead of None would make the behavior more uniform, but it would break the code if text.count(begin, end) which just checks where there is something in the interval.

I think that the decision of returning 1-tuple for a single count (unless it is zero) was a mistake. The Tk code is different for a single count and multiple code -- a single count is returned as an integer instead of a 1-list. The difference is only disappeared if convert it to string.

It would be more convenient for users to get an integer in Python too. But it is a breaking change. Choosing between two breaking changes, returning (0,) for an empty count or returning a single count as integer, I prefer the latter.

(cherry picked from commit 1b684c8) Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>

…t.count() Previously they were silently ignored. Now they are errors.

(cherry picked from commit 1b684c8) Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>

…t() (GH-98436) Previously they were silently ignored. Now they are errors.

…t.count() (pythonGH-98436) Previously they were silently ignored. Now they are errors. (cherry picked from commit e4ec8de) Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>

…t() (GH-98436) Previously they were silently ignored. Now they are errors. (cherry picked from commit e4ec8de) Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>

It now always returns an integer if one or less counting options are specified. Previously it could return a single count as a 1-tuple, an integer (only if option "update" was specified) or None if no items found. The result is now the same if wantobjects is set to 0.

terryjreedy · 2023-10-24T14:56:07Z

Thanks for the fix.

serhiy-storchaka · 2023-11-28T08:47:32Z

It was suggested to partially restore the old behavior and add an optional argument return_ints to control the returned value.

terryjreedy · 2023-11-28T13:15:25Z

I clicked and read most of that discussion.

…) by default By default, it preserves an inconsistent behavior of older Python versions: packs the count into a 1-tuple if only one or none options are specified (including 'update'), returns None instead of 0. Except that setting wantobjects to 0 no longer affects the result. Add a new parameter return_ints: specifying return_ints=True makes Text.count() always returning the single count as an integer insteaf of a 1-tuple or None.

…efault (GH-115031) By default, it preserves an inconsistent behavior of older Python versions: packs the count into a 1-tuple if only one or none options are specified (including 'update'), returns None instead of 0. Except that setting wantobjects to 0 no longer affects the result. Add a new parameter return_ints: specifying return_ints=True makes Text.count() always returning the single count as an integer instead of a 1-tuple or None.

…-98484) It now always returns an integer if one or less counting options are specified. Previously it could return a single count as a 1-tuple, an integer (only if option "update" was specified) or None if no items found. The result is now the same if wantobjects is set to 0.

…) by default (pythonGH-115031) By default, it preserves an inconsistent behavior of older Python versions: packs the count into a 1-tuple if only one or none options are specified (including 'update'), returns None instead of 0. Except that setting wantobjects to 0 no longer affects the result. Add a new parameter return_ints: specifying return_ints=True makes Text.count() always returning the single count as an integer instead of a 1-tuple or None.

…-98484) It now always returns an integer if one or less counting options are specified. Previously it could return a single count as a 1-tuple, an integer (only if option "update" was specified) or None if no items found. The result is now the same if wantobjects is set to 0.

ronaldoussoren added the topic-tkinter label Oct 10, 2022

serhiy-storchaka self-assigned this Oct 14, 2022

serhiy-storchaka added a commit to serhiy-storchaka/cpython that referenced this issue Oct 14, 2022

pythongh-97928: Add tests for tkinter.Text.count()

0d67dfd

This was referenced Oct 14, 2022

gh-97928: Add tests for tkinter.Text.count() #98269

Merged

[3.11] gh-97928: Add tests for tkinter.Text.count() (GH-98269) #98434

Merged

[3.10] gh-97928: Add tests for tkinter.Text.count() (GH-98269) #98435

Merged

serhiy-storchaka added a commit that referenced this issue Oct 19, 2022

gh-97928: Add tests for tkinter.Text.count() (GH-98269)

1b684c8

miss-islington pushed a commit to miss-islington/cpython that referenced this issue Oct 19, 2022

pythongh-97928: Add tests for tkinter.Text.count() (pythonGH-98269)

1763a5b

(cherry picked from commit 1b684c8) Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>

miss-islington pushed a commit to miss-islington/cpython that referenced this issue Oct 19, 2022

pythongh-97928: Add tests for tkinter.Text.count() (pythonGH-98269)

49bf70f

(cherry picked from commit 1b684c8) Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>

serhiy-storchaka added a commit to serhiy-storchaka/cpython that referenced this issue Oct 19, 2022

pythongh-97928: Fix handling options starting with "-" in tkinter.Tex…

2a113a6

…t.count() Previously they were silently ignored. Now they are errors.

bedevere-bot mentioned this issue Oct 19, 2022

gh-97928: Fix handling options starting with "-" in tkinter.Text.count() #98436

Merged

miss-islington added a commit that referenced this issue Oct 19, 2022

gh-97928: Add tests for tkinter.Text.count() (GH-98269)

d0ed05c

(cherry picked from commit 1b684c8) Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>

miss-islington added a commit that referenced this issue Oct 19, 2022

gh-97928: Add tests for tkinter.Text.count() (GH-98269)

a847255

(cherry picked from commit 1b684c8) Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>

This was referenced Oct 19, 2022

[3.11] gh-97928: Fix handling options starting with "-" in tkinter.Text.count() (GH-98436) #98438

Merged

[3.10] gh-97928: Fix handling options starting with "-" in tkinter.Text.count() (GH-98436) #98439

Merged

serhiy-storchaka added a commit that referenced this issue Oct 19, 2022

gh-97928: Fix handling options starting with "-" in tkinter.Text.coun…

e4ec8de

…t() (GH-98436) Previously they were silently ignored. Now they are errors.

serhiy-storchaka added a commit to serhiy-storchaka/cpython that referenced this issue Oct 20, 2022

pythongh-97928: Fix tkinter.Text.count()

a330207

bedevere-bot mentioned this issue Oct 20, 2022

gh-97928: Change the behavior of tkinter.Text.count() #98484

Merged

serhiy-storchaka added the 3.13 bugs and security fixes label Oct 24, 2023

serhiy-storchaka closed this as completed Oct 24, 2023

serhiy-storchaka reopened this Nov 28, 2023

bedevere-app bot mentioned this issue Feb 5, 2024

gh-97928: Partially restore the behavior of tkinter.Text.count() by default #115031

Merged

serhiy-storchaka closed this as completed Feb 11, 2024

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tkinter.Text.count(index1, index2) returns None not (0,) when index1 equals index2 #97928

tkinter.Text.count(index1, index2) returns None not (0,) when index1 equals index2 #97928

RogerMarsh commented Oct 5, 2022 •

edited by bedevere-app bot

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serhiy-storchaka commented Oct 14, 2022

terryjreedy commented Oct 24, 2023

serhiy-storchaka commented Nov 28, 2023

terryjreedy commented Nov 28, 2023

tkinter.Text.count(index1, index2) returns None not (0,) when index1 equals index2 #97928

tkinter.Text.count(index1, index2) returns None not (0,) when index1 equals index2 #97928

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RogerMarsh commented Oct 5, 2022 • edited by bedevere-app bot Loading

Linked PRs

serhiy-storchaka commented Oct 14, 2022

terryjreedy commented Oct 24, 2023

serhiy-storchaka commented Nov 28, 2023

terryjreedy commented Nov 28, 2023

RogerMarsh commented Oct 5, 2022 •

edited by bedevere-app bot

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