New submission from Terry J. Reedy:
The signature for tkinter class Variable and its subclasses StringVar, IntVar,
DoubleVar, BooleanVar is
def __init__(self, master=None, value=None, name=None):
However, the None default is invalid because of
self._tk = master.tk
The preceding lines
if not master:
master = _default_root
might suggest that None is acceptible. But _default_root is set to None at the
top of the file, so that just replaces None with None.
If Variables must have a gui widget parent, then they cannot be used in
gui-free tests, even though they have no graphic representation.
Moveover, not everything is a proper master. configSectionNameDialog.py .
GetCfgSectionNameDialog(Toplevel) . Create.Widgets(self) has these lines:
self.name = StringVar(self)
self.fontSize = StringVar(self)
However, these are not (always) garbage collectable.
After fixing the dialog test at the bottom of the file, and running it with 3.3
python_d -m idlelib.configSectionNameDialog (#18130), and adding the gc flag, I
repeatedly got
[sys:1: ResourceWarning: gc: 2 uncollectable objects at shutdown
[<tkinter.StringVar object at 0x02C597E0>, <tkinter.StringVar ...]]
(This only showed when running from the console, not when running within Idle
started within the interactive debug interpreter.)
Running the test multiple times within a session, by repeatedly creating new
dialogs with the [dialog] button in the test window, multiplied the uncollected
objects.
Replacing 'self' with 'self.parent' solved the problem, at least in the test
situation.
----------
components: Tkinter
messages: 190574
nosy: gpolo, terry.reedy
priority: normal
severity: normal
stage: needs patch
status: open
title: Tkinter Variables require a proper master
type: behavior
versions: Python 2.7, Python 3.3, Python 3.4
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Python tracker <[email protected]>
<http://bugs.python.org/issue18131>
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