R help - Aug 2007 - gWidgets (tcltk): problem extracting values from widgets in glayout grid

Hello,

I haven't been able to find an example for the second case below -- or
perhaps I didn't recognize it when I saw it.
Is there a value for x such that svalue(x) will return "bbb", either
by
itself or as part of an array? Or do I need to do something else
entirely?
(R2.5.1; Windows XP)
> ####  gWidgets test
> options("guiToolkit"="tcltk")
> require(gWidgets)
[1] TRUE
>
> ###### Case 1: this works ########
> wtesta = gwindow("wtesta",visible=TRUE)
> wtesta1 = gedit("aaa",container=wtesta)
> print(svalue(wtesta1))
[1] "aaa"
>
> ### Case 2: this makes an identical window & widget, with "b"
replacing "a"
> ### but does't return the value
> wtesta = gwindow("wtestb",visible=TRUE)
> wtestb = glayout(visible=TRUE,container=wtesta)
> wtestb[1,1]=gedit("bbb",container=wtestb)
> print(svalue(wtestb[1,1]))
Error in function (classes, fdef, mtable)  :
        unable to find an inherited method for function
".leftBracket",
for signature "gLayouttcltk", "guiWidgetsToolkittcltk"
Error in svalue(wtestb[1, 1]) : error in evaluating the argument 'obj'
in selecting a method for function 'svalue'
> print(svalue(wtestb))
Error in function (classes, fdef, mtable)  :
        unable to find an inherited method for function ".svalue", for
signature "gLayouttcltk", "NULL", "NULL",
"guiWidgetsToolkittcltk"

Evan Englund
U.S. EPA
702-798-2248

Dear Evan, 
<englund.evan <at> epamail.epa.gov> writes:
> 
> 
> Hello,
> 
> I haven't been able to find an example for the second case below -- or
> perhaps I didn't recognize it when I saw it.
> Is there a value for x such that svalue(x) will return "bbb",
either by
> itself or as part of an array? Or do I need to do something else
> entirely?
> (R2.5.1; Windows XP)
> 
You will need to store the widget. See below.
> > ### Case 2: this makes an identical window & widget, with
"b"
> replacing "a"
> > ### but does't return the value
> > wtesta = gwindow("wtestb",visible=TRUE)
> > wtestb = glayout(visible=TRUE,container=wtesta)
> > wtestb[1,1]=gedit("bbb",container=wtestb)
> > print(svalue(wtestb[1,1]))

the glayout container doesn't work that way. You don't get a [
method, just a [<- one. Try something like this instead to store the widget:

wtestb[1,1]=(bbb <- gedit("bbb",container=wtestb) )
print(svalue(bbb))

--John

> Evan Englund
> U.S. EPA
> 702-798-2248
> 
> ______________________________________________
> R-help <at> stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
> 
>

Thanks, John. That works...  The following is a trivial but complete
application that uses glayout to
position the widgets, then lets you edit a parameter and execute a
function that uses the parameter:

##################################
### glayout example
wtesta = gwindow("Sample Histogram",visible=TRUE)
wtestb = glayout(visible=TRUE,container=wtesta)
wtestb[1,1] = glabel("Population Mean",container=wtestb)
### the gedit widget is assigned to "gWpopmean" for future reference
wtestb[2,1] = (gWpopmean = gedit("10",container=wtestb,width=5))
wtestb[2,2] = gbutton("Plot
Histogram",container=wtestb,handler=function(h,...){myplot()})
myplot = function()
  {
  popmean = as.numeric(svalue(gWpopmean))
  hist(rnorm(100,popmean,1))
  }
####################################


Dear Evan,
<englund.evan <at> epamail.epa.gov> writes:
>
>
> Hello,
>
> I haven't been able to find an example for the second case below -- or
> perhaps I didn't recognize it when I saw it.
> Is there a value for x such that svalue(x) will return "bbb",
either
by
> itself or as part of an array? Or do I need to do something else
> entirely?
> (R2.5.1; Windows XP)
>
You will need to store the widget. See below.
> > ### Case 2: this makes an identical window & widget, with
"b"
> replacing "a"
> > ### but does't return the value
> > wtesta = gwindow("wtestb",visible=TRUE)
> > wtestb = glayout(visible=TRUE,container=wtesta)
> > wtestb[1,1]=gedit("bbb",container=wtestb)
> > print(svalue(wtestb[1,1]))

the glayout container doesn't work that way. You don't get a [
method, just a [<- one. Try something like this instead to store the
widget:

wtestb[1,1]=(bbb <- gedit("bbb",container=wtestb) )
print(svalue(bbb))

--John


Evan Englund
U.S. EPA
702-798-2248