Hi,
I apologize if this is not the proper forum.
I am writing a package to automatically create RGtk GUI's with an
arbitrary number of widgets to act as a "control panel" front end for a
user-specified plotting or simulation function. The widgets are
specified in a list argument to a function and associated with specific
parameter values for the user function (FUN), which is called whenever a
widget value is modified. For example, a call to:
makegui <- function (w=list(x=100, y=200, FUN)) {...}
would result in a GUI with slider widgets for parameters "x" and "y".
Whenever the sliders are changed, the function FUN is called with the
new value of "x" or "y" -- possibly drawing a plot or something else.
MY PROBLEM IS THIS: I want to make callbacks for each widget that
automatically send new parameter values to the function FUN, but I can't
find a way to do this with arbitrary numbers of widgets/parameters and
arbitrary names for the widgets. For convenience, I set the parameter
names to be the same as the widget names.
First I store all initial parameter values in an array, e.g., params <-
list(x=100, y=200). widget.names <- c("x", "y")
I create each widget with something like:
assign(widget.name, gtkWidget(...))
Then I add a callback:
get(widget.name)$AddCallback("value-changed", function(w)
{callbackFUN(...)})
I want the callbackFUN() function to be able to get the widget's value
with something like w$GetValue() and put it into the "params" list, and
then finally to send the parameter list to the FUN function.
I can't seem to find any way to send a character string of the
appropriate arbitrary widget name to the callback function so that I can
put the widget value into the parameter list. I've tried setting an
attribute of the widget with its associated parameter name when I create
the callback, but the attribute seems to disappear when the callback is
called.
I can get around all this whole problem by simply looping through all of
the widgets at once by name:
for (i in widget.names) params[[i]] <- get(i)$GetValue()
but this approach is inefficient when only one parameter is changed at a
time.
Am I missing something easy?
TIA for any ideas.
--Neil Klepeis
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