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Add new methods to trace Tkinter variables #66313

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Add new methods to trace Tkinter variables#66313
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serhiy-storchaka
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topic-tkintertype-featureA feature request or enhancement

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@serhiy-storchaka
serhiy-storchaka
opened on Jul 31, 2014
BPO 22115
Nosy @terryjreedy, @serhiy-storchaka
Files
  • tkinter_trace_variable_3.patch
  • tkinter_trace_variable_4.patch
  • tkinter_trace_variable_5.patch
  • tkinter_trace_variable_6.patch
    		•

    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/serhiy-storchaka'
closed_at = <Date 2016-06-26.14:51:23.278>
created_at = <Date 2014-07-31.14:47:51.769>
labels = ['type-feature', 'expert-tkinter']
title = 'Add new methods to trace Tkinter variables'
updated_at = <Date 2016-06-26.14:51:23.248>
user = 'https://github.com/serhiy-storchaka'

    bugs.python.org fields:

    activity = <Date 2016-06-26.14:51:23.248>
actor = 'serhiy.storchaka'
assignee = 'serhiy.storchaka'
closed = True
closed_date = <Date 2016-06-26.14:51:23.278>
closer = 'serhiy.storchaka'
components = ['Tkinter']
creation = <Date 2014-07-31.14:47:51.769>
creator = 'serhiy.storchaka'
dependencies = []
files = ['36395', '36404', '43466', '43539']
hgrepos = []
issue_num = 22115
keywords = ['patch']
message_count = 13.0
messages = ['224407', '225449', '225479', '225490', '268845', '269092', '269253', '269272', '269276', '269277', '269280', '269288', '269290']
nosy_count = 3.0
nosy_names = ['terry.reedy', 'python-dev', 'serhiy.storchaka']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue22115'
versions = ['Python 2.7', 'Python 3.5', 'Python 3.6']

    Activity

    1. serhiy-storchaka commented on Jul 31, 2014

      @serhiy-storchaka
      serhiy-storchaka
      on Jul 31, 2014
      MemberAuthor

      Command used to monitor Tcl variable access ("trace variable", "trace vdelete", "trace vinfo") are deprecated and will likely be removed in a future version of Tcl. Replacements ("trace add variable", "trace remove variable", "trace info variable") use slightly different syntax (operations are specified as a list of words "array", "read", "write" and "unset" instead of a string containing characters "a", "r", "w" and "u"). Therefore we need new set of methods.

      Proposed preliminary patch adds trace_add, trace_remove and trace_info methods to the Variable class. It will be changed after applying bpo-22068 patch. Tests for old methods will be backported to older Python versions.

    2. serhiy-storchaka
      added
      topic-tkinter
      type-featureA feature request or enhancement
      on Jul 31, 2014

    3. serhiy-storchaka commented on Aug 17, 2014

      @serhiy-storchaka
      serhiy-storchaka
      on Aug 17, 2014
      MemberAuthor

      Synchronized with the tip.

    4. terryjreedy commented on Aug 18, 2014

      @terryjreedy
      terryjreedy
      on Aug 18, 2014
      Member

      trace_add:

      "list or tuple" (of such strings.) Can we say 'sequence' (or even set or iterable) or is the requirement specifically tuple or list?

      Does tk call the traceback function with any args it supplies(other than those passed in)? (In other words, is the callback affected by the bpo-22214 proposal?)

      *args is a tuple of objects, not parameters (names). I would just say "Additional arguments are passed to the traceback call".

      trace_remove:

      "Should be same as were specified in trace_add()." Is a subset not allowed to remove a subset of the registrations currently allowed? Does trying to delete other modes raise TclError? If both are so, I would say something like "Must be a subset of current trace modes.".

      "Additional parameters should be same as were specified in trace_add()."
      Again, /parameters/arguments/. That aside, remembering and passing the arguments back seems like a bizarre requirement that makes not sense. What happens if one does not, or gets it wrong? It the args are really required exactly, then is seems that trace_add should return (cbname,) + args to be passed back to trace_remove as cbname_args.

      Alternatively, could *args (and mode) be retrieved from trace_info?

      trace_variable, _vdelete

      " This method is deprecated and will likely be removed in a future version of Tcl." Slightly more accurate would be "This deprecated method wraps a deprecated tcl method that will likely be removed in the future."

    5. serhiy-storchaka commented on Aug 18, 2014

      @serhiy-storchaka
      serhiy-storchaka
      on Aug 18, 2014
      MemberAuthor

      "list or tuple" (of such strings.) Can we say 'sequence' (or even set or
      iterable) or is the requirement specifically tuple or list?

      No. The call() method accepted only tuples, and since bpo-21525 it now
      supports lists.

      Does tk call the traceback function with any args it supplies(other than
      those passed in)? (In other words, is the callback affected by the bpo-22214
      proposal?)

      Tcl calls the traceback function with stringified arguments. No, this is not
      affected by the bpo-22214 proposal. And only types which are supported by Tkinter
      (int, bool, float, str, bytes, tuple, list, Tcl_Obj) are allowed. But this
      behavior can be changed in future versions of Tcl..

      "Should be same as were specified in trace_add()." Is a subset not allowed
      to remove a subset of the registrations currently allowed? Does trying to
      delete other modes raise TclError? If both are so, I would say something
      like "Must be a subset of current trace modes.".

      Unfortunately both are no. If you pass wrong mode, trace_remove() will
      silently finished, but next attempt to call a callback will raise TclError
      (because a command is already deleted). Fixed in next patch and should be
      backported.

      That aside, remembering and passing the
      arguments back seems like a bizarre requirement that makes not sense. What
      happens if one does not, or gets it wrong?

      Same bad things as when pass wrong mode.

      It the args are really required
      exactly, then is seems that trace_add should return (cbname,) + args to be
      passed back to trace_remove as cbname_args.

      Looks good.

      Alternatively, could *args (and mode) be retrieved from trace_info?

      You can retrieve mode, cbname and (stringified) args from trace_info. Currently
      following code removes all callbacks from variable:

      for mode, cbname_args in v.trace_info():
    v.trace_remove(mode, *cbname_args)

      With next patch '*' is not needed.

      Thank you for the review. Updated patch addresses all your comments.

    6. serhiy-storchaka commented on Jun 19, 2016

      @serhiy-storchaka
      serhiy-storchaka
      on Jun 19, 2016
      MemberAuthor

      Updated patch provides simplified interface. The support of passing callback arguments is removed. This complicates an interface and is not needed since Python supports closure and the support of callback arguments was more limited (supported only limited set of types and arguments are converted to str).

      Added an entry in What's News.

    7. serhiy-storchaka
      self-assigned this
      on Jun 19, 2016

    8. terryjreedy commented on Jun 22, 2016

      @terryjreedy
      terryjreedy
      on Jun 22, 2016
      Member

      I gather that 'add', 'delete', and 'info' replace 'variable', 'vdelete', and 'vinfo'. Also see review. Deprecation period should be fairly long. Of course, a currently hypothetical tcl/tk 9.0 with old stuff gone would make it immediate for users of 9.0.

      Applies cleanly and tests pass, but do not hardly interact with the patch. More importantly, IDLE starts fresh, option dialog comes up and appears to work. So old functions continue to work.

      The real test from IDLE would be to recode configdialog to use the new functions and then test. I am thinking about how to test configdialog enough that I am willing to refactor it for real.

    9. serhiy-storchaka commented on Jun 25, 2016

      @serhiy-storchaka
      serhiy-storchaka
      on Jun 25, 2016
      MemberAuthor

      Thank you for your review Terry. Here is updated patch. IDLE now uses new API.

    10. terryjreedy commented on Jun 26, 2016

      @terryjreedy
      terryjreedy
      on Jun 26, 2016
      Member

      What's New: patchcheck found trailing whitespace to remove; it contains some additions that appear to belong to another issue.

      configdialog change looks good and dialog still works.

      I am expecting to add more Vars sometime soon, though probably not in the next few days. Before I do, I want to reduce the repetition of names and remove the repetition of trace_add calls. I just opened bpo-27388.

    11. serhiy-storchaka commented on Jun 26, 2016

      @serhiy-storchaka
      serhiy-storchaka
      on Jun 26, 2016
      MemberAuthor

      Maybe omit the mention of the array mode since it can't be used with variables created with Tkinter wrapper?

    12. terryjreedy commented on Jun 26, 2016

      @terryjreedy
      terryjreedy
      on Jun 26, 2016
      Member

      Good idea. Anyone who knows enough to create one by calling into tcl, assuming that is possible, should know that the methods apply. Everyone else, like me, will just be confused.

    13. python-dev commented on Jun 26, 2016

      @python-dev
      python-devmannequin
      on Jun 26, 2016
      Mannequin

      New changeset a201180c0f77 by Serhiy Storchaka in branch 'default':
      Issue bpo-22115: Added methods trace_add, trace_remove and trace_info in the
      https://hg.python.org/cpython/rev/a201180c0f77

    14. python-dev commented on Jun 26, 2016

      @python-dev
      python-devmannequin
      on Jun 26, 2016
      Mannequin

      New changeset 77378dce6bcf by Serhiy Storchaka in branch '2.7':
      Issue bpo-22115: Fixed tracing Tkinter variables.
      https://hg.python.org/cpython/rev/77378dce6bcf

      New changeset 293ec9547334 by Serhiy Storchaka in branch '3.5':
      Issue bpo-22115: Fixed tracing Tkinter variables:
      https://hg.python.org/cpython/rev/293ec9547334

      New changeset c4839c36a71f by Serhiy Storchaka in branch 'default':
      Issue bpo-22115: Updated Misc/NEWS.
      https://hg.python.org/cpython/rev/c4839c36a71f

    15. serhiy-storchaka commented on Jun 26, 2016

      @serhiy-storchaka
      serhiy-storchaka
      on Jun 26, 2016
      MemberAuthor

      Backported fixes for old tracing methods. Unfortunately the tracing in the "u" mode doesn't work in 2.7. This is related to some differences in GC. I don't think this is important and close this issue.

    16. serhiy-storchaka
      closed this as completedon Jun 26, 2016
    17. ezio-melotti
      transferred this issue fromon Apr 10, 2022
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