R gWidgets2 doesn't return values - r

Question

I am trying to make an input form with gWidgets2 to write your name, select a time period and select a car. These input values are the saved into a list. The data is following:
list.timeinterval = c("last month", "last year", "Specific Period")
list.vehicle = c("car1", "car2", "car3")
This is my code:
choose.specs <- function(list.timeinterval, list.vehicle){
library(gWidgets2)
library(gWidgets2tcltk)
options(guiToolkit = "tcltk")
reporter <- NULL
period <- NULL
vehicle <- NULL
w <- gwindow("Choose report specification")
g <- ggroup(horizontal = FALSE, cont = w)
tmp <- gframe("Reporter name", cont = g, expand = TRUE)
rep <- gedit("write your name",
cont = tmp,
handler = function(...)
reporter = svalue(rep))
tmp <- gframe("Choose time intervall", cont = g, expand = TRUE)
per <- gcombobox(list.timeinterval,
label = "Select time period",
editable = FALSE,
cont = tmp,
handler = function(...)
period = svalue(per))
tmp <- gframe("Choose car", cont = g, expand = TRUE)
car <- gcombobox(list.vehicle,
label = "Select car:",
editable = FALSE,
cont = tmp,
handler = function(...)
vehicle = svalue(car))
visible(tmp, set = TRUE)
btn <- gbutton("confirm", cont = g)
addHandlerClicked(btn, handler = function(h,...) {
dispose(w)
})
return(list(reporter,
period,
vehicle))
}
list.specs <- choose.specs(list.timeinterval, list.vehicle)
Somehow it returns an empty list. If i don't set reporter, period and fleet = NULL it gives an error "object reporter not found".
If i write this return(list(svalue(rep), svalue(per), svalue(car))) instead of return(list(reporter, period, vehicle)) it returns the default values
[[1]]
[1] "write your name"
[[2]]
[1] "last month"
[[3]]
[1] "car1"
how can i return this input values?
EDIT:
My interpretation of the suggested solution from #jverzani is following:
choose.specs <- function(list.timeinterval, list.vehicle){
library(gWidgets2)
library(gWidgets2tcltk)
options(guiToolkit = "tcltk")
reporter <- NULL
period <- NULL
fleets <- NULL
e <- new.env()
e$reporter <- reporter
e$period <- period
e$fleets <- fleets
w <- gwindow("Choose report specification")
g <- ggroup(horizontal = FALSE, cont = w)
tmp <- gframe("Reporter name", cont = g, expand = TRUE)
rep <- gedit("write your name",
cont = tmp,
handler = function(...)
e$reporter <- svalue(rep))
tmp <- gframe("Choose time intervall", cont = g, expand = TRUE)
per <- gcombobox(list.timeinterval,
label = "Select time period",
editable = FALSE,
cont = tmp,
handler = function(...)
e$period <- svalue(per))
tmp <- gframe("Choose car", cont = g, expand = TRUE)
car <- gcombobox(list.vehicle,
label = "Select car:",
editable = FALSE,
cont = tmp,
handler = function(...)
e$fleets <- svalue(car))
visible(tmp, set = TRUE)
btn <- gbutton("confirm", cont = g)
addHandlerClicked(btn, handler = function(h,...) {
dispose(w)
})
return(list(e$reporter,
e$period,
e$vehicle))
}
and/or:
choose.specs <- function(list.timeinterval, list.vehicle){
library(gWidgets2)
library(gWidgets2tcltk)
options(guiToolkit = "tcltk")
reporter <- NULL
period <- NULL
vehicle <- NULL
w <- gwindow("Choose report specification")
g <- ggroup(horizontal = FALSE, cont = w)
tmp <- gframe("Reporter name", cont = g, expand = TRUE)
rep <- gedit("write your name",
cont = tmp,
handler = function(...)
reporter <<- svalue(rep))
tmp <- gframe("Choose time intervall", cont = g, expand = TRUE)
per <- gcombobox(list.timeinterval,
label = "Select time period",
editable = FALSE,
cont = tmp,
handler = function(...)
period <<- svalue(per))
tmp <- gframe("Choose car", cont = g, expand = TRUE)
car <- gcombobox(list.vehicle,
label = "Select car:",
editable = FALSE,
cont = tmp,
handler = function(...)
vehicle <<- svalue(car))
visible(tmp, set = TRUE)
btn <- gbutton("confirm", cont = g)
addHandlerClicked(btn, handler = function(h,...) {
dispose(w)
})
return(list(reporter,
period,
vehicle))
}
Unfortunately still the same issues.

Answer 1

You can't return values from a handler (except for the modal dialogs). You need to assign them. Typically this is done with <<- or an environment, so that modifications within the function body happen outside the scope of the body. For example, in the list.timeinterval handler you might write e$period = ... where e is some environment you initialize before displaying the GUI.
Your return value happens instantly. Rather, you need to assign values in the handler to something persistent. Here is one pattern:
library(gWidgets2)
library(gWidgets2tcltk)
options(guiToolkit = "tcltk")
e = new.env()
choose.specs <- function(e, list.timeinterval, list.vehicle){
e$reporter <- NULL
e$period <- NULL
e$vehicle <- NULL
w <- gwindow("Choose report specification")
g <- ggroup(horizontal = FALSE, cont = w)
tmp <- gframe("Reporter name", cont = g, expand = TRUE)
rep <- gedit("write your name",
cont = tmp,
handler = function(...)
e$reporter <<- svalue(rep))
tmp <- gframe("Choose time intervall", cont = g, expand = TRUE)
per <- gcombobox(list.timeinterval,
label = "Select time period",
editable = FALSE,
cont = tmp,
handler = function(...)
e$period <<- svalue(per))
tmp <- gframe("Choose car", cont = g, expand = TRUE)
car <- gcombobox(list.vehicle,
label = "Select car:",
editable = FALSE,
cont = tmp,
handler = function(...)
e$vehicle <<- svalue(car))
visible(tmp, set = TRUE)
btn <- gbutton("confirm", cont = g)
addHandlerClicked(btn, handler = function(h,...) {
dispose(w)
})
# return(list(reporter,
# period,
# vehicle))
}
When you interact with the dialong, the e environment updates.