[Tcl-bugs] [ tktoolkit-Bugs-3460403 ] Ttk async proc resets result of a command in main script

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Bugs item #3460403, was opened at 2011-12-15 14:44
Message generated for change (Tracker Item Submitted) made by eugene_cdn
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Category: 88. Themed Tk
Group: obsolete: 8.5.8
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Yevgen Ryazanov (eugene_cdn)
Assigned to: Joe English (jenglish)
Summary: Ttk async proc resets result of a command in main script

Initial Comment:
I found that in the middle of execution the result of [info library] was empty.  To localize the problem, I called info library many times and at some call the result was empty, then back to normal.  After setting a watch point on object result, I found that Ttk's procedure ThemeChangedProc called Tcl_GlobalEval without preserving Tcl result.  Here's an example of stack where the result of [info library] is nullified:

  [1] libtcl.so:ResetObjResult(iPtr = 0x85b03b8), line 968 in "tclResult.c"
  [2] libtcl.so:Tcl_ResetResult(interp = (nil)), line 896 in "tclResult.c"
  [3] libtcl.so:TclEvalEx(interp = 0x85b03b8, script = 0xf697895c "ttk::ThemeChanged", numBytes = 17, flags = 0, line = 1), line 4089 in "tclBasic.c"
  [4] libtcl.so:Tcl_EvalEx(interp = 0x85b03b8, script = 0xf697895c "ttk::ThemeChanged", numBytes = -1, flags = 0), line 4043 in "tclBasic.c"
  [5] libtcl.so:Tcl_Eval(interp = 0x85b03b8, script = 0xf697895c "ttk::ThemeChanged"), line 4823 in "tclBasic.c"
  [6] libtcl.so:Tcl_GlobalEval(interp = 0x85b03b8, command = 0xf697895c "ttk::ThemeChanged"), line 5836 in "tclBasic.c"
  [7] libtk.so:ThemeChangedProc(clientData = 0x860e818), line 519 in "ttkTheme.c"
  [8] libtcl.so:TclServiceIdle(), line 738 in "tclTimer.c"
  [9] libtcl.so:Tcl_DoOneEvent(flags = 34), line 991 in "tclNotify.c"
  [10] libtk.so:MapFrame(clientData = 0x85d2c80), line 1751 in "tkFrame.c"
  [11] libtcl.so:TclServiceIdle(), line 738 in "tclTimer.c"
  [12] libtcl.so:Tcl_DoOneEvent(flags = -1), line 991 in "tclNotify.c"
  [13] libeclutil.so:EventHandlerProc( = (nil), interp = 0x85b03b8, code = 0), line 367 in "gnm.C"
  [14] libtcl.so:Tcl_AsyncInvoke(interp = 0x85b03b8, code = 0), line 240 in "tclAsync.c"
  [15] libtcl.so:TclEvalObjvInternal(interp = 0x85b03b8, objc = 1, objv = 0x86723e0, command = (nil), length = 0, flags = 524288), line 3697 in "tclBasic.c"
  [16] libtcl.so:Tcl_EvalObjv(interp = 0x85b03b8, objc = 1, objv = 0x86723e0, flags = 524288), line 3886 in "tclBasic.c"
  [17] libtcl.so:NsEnsembleImplementationCmd(clientData = 0x85bf0e0, interp = 0x85b03b8, objc = 2, objv = 0x86722d8), line 6233 in "tclNamesp.c"
  [18] libtcl.so:TclEvalObjvInternal(interp = 0x85b03b8, objc = 2, objv = 0x86722d8, command = 0x8088722 "info library] / $tcl_library"", length = 12, flags = 0), line 3690 in "tclBasic.c"
  [19] libtcl.so:TclEvalEx(interp = 0x85b03b8, script = 0x8088722 "info library] / $tcl_library"", numBytes = 12, flags = 0, line = 1), line 4338 in "tclBasic.c"
  [20] libtcl.so:TclSubstTokens(interp = 0x85b03b8, tokenPtr = 0x8671ee8, count = 4, tokensLeftPtr = (nil), line = 1), line 2254 in "tclParse.c"
  [21] libtcl.so:TclEvalEx(interp = 0x85b03b8, script = 0x8088714 "puts "lib4 = [info library] / $tcl_library"", numBytes = 43, flags = 0, line = 1), line 4232 in "tclBasic.c"
  [22] libtcl.so:Tcl_EvalEx(interp = 0x85b03b8, script = 0x8088714 "puts "lib4 = [info library] / $tcl_library"", numBytes = -1, flags = 0), line 4043 in "tclBasic.c"
  [23] libtcl.so:Tcl_Eval(interp = 0x85b03b8, script = 0x8088714 "puts "lib4 = [info library] / $tcl_library""), line 4823 in "tclBasic.c"

I checked the latest Tk sources, 8.6b2, and the code of the function is the same.
After I added Tcl_SaveResult and Tcl_RestoreResult to the function, the problem is gone.
This change fixes the problem for me:

   % cleartool diff -diff -pre ttkTheme.c
   518c518,519
   <
   ---
   >     Tcl_SavedResult state;
   >     Tcl_SaveResult (pkgPtr->interp, &state);
   521a523
   >     Tcl_RestoreResult (pkgPtr->interp, &state);

You may want to preserve the whole state, not only result.
Good luck!

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