gh-123193: Document tkinter Variable lifetime#152625
Open
serhiy-storchaka wants to merge 1 commit into
Open
Conversation
A Tk variable wrapper unsets its Tcl variable when garbage collected, so a reference must be kept while a widget uses it. Otherwise Tk recreates the Tcl variable but never unsets it again, leaking it. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
serhiy-storchaka
added
needs backport to 3.13
Documentation build overview
|
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
A Tk variable wrapper (
StringVar,IntVar, ...) unsets its Tcl variable when the Python object is garbage collected.If the wrapper is dropped while a widget still references it (through
variable/textvariable), Tk recreates the Tcl variable to keep the widget working, but it is then no longer managed by Python and is never unset again — so it leaks.This is the cause of gh-123193: dynamically creating widgets whose
Variableobjects are kept only in local variables (and thus collected while the widgets live on) steadily accumulates orphanedPY_VAR*Tcl globals.It is the documented "keep a reference to your
Variable" footgun rather than a fixable_tkinterbug, so this just documents the lifetime contract — on thecoupling-widget-variablestutorial and on theVariableclass.