Re: Test for dialog existence

*To*: mathgroup at smc.vnet.net*Subject*: [mg112750] Re: Test for dialog existence*From*: John Fultz <jfultz at wolfram.com>*Date*: Wed, 29 Sep 2010 04:14:05 -0400 (EDT)

On Tue, 28 Sep 2010 06:01:47 -0400 (EDT), Chris Degnen wrote: > Hi. Can anyone suggest how to test for the existence of a dialog? > > In the example below a dialog is created containing a plot which can > be modified. However it seems to be difficult to test whether the > dialog has been closed. > > This creates the dialog: > > BeginPackage["TestExample`TestDialog`"]; > CreateTestDialog::usage = "CreateTestDialog[] creates a test dialog"; > Begin["`Private`"]; > CreateTestDialog[] := > Module[{}, n = 4; > CreateDialog[ > plot = Dynamic[ > ParametricPlot[{Sin[t], Sin[n t]}, {t, 0, 2 Pi}, Ticks -> None, > ImageSize -> 100]]]]; > End[]; > EndPackage[]; > > CreateTestDialog[]; > > > And the plot can be modified by various means: > > TestExample`TestDialog`Private`n = 8; > > TestExample`TestDialog`Private`n = 2; > > > But how can I tell if the dialog has been closed? The dynamic plot > object still shows as existing afterwards: > > NameQ["TestExample`TestDialog`Private`plot"] Yes, the name and even the value remain because they aren't scoped in any way. CreateDialog is not a variable scoping construct. If you want to poll to test whether it's been closed, you can do this using the NotebookObject returned by your CreateTestDialog function. I.e., nb=CreateTestDialog[]; NotebookInformation[nb] This will return a list of values if the notebook is still open, and $Failed if it's been closed. If you want to be notified as soon as the dialog closes, then the best way to do this is to implement a dialog with a DefaultButton[] and/or a CancelButton[]. Sincerely, John Fultz jfultz at wolfram.com User Interface Group Wolfram Research, Inc.