R gWidgets2不返回值

Question

我正在尝试用gWidgets2做一个输入表单，写下你的名字，选择一个时间段，然后选择一辆车。这些输入值被保存到列表中。数据如下：

list.timeinterval = c("last month", "last year", "Specific Period")
list.vehicle = c("car1", "car2", "car3")

这是我的代码：

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)

不知何故，它返回一个空列表。如果我没有设置reporter，period and fleet = NULL，它会给出一个错误"object reporter found“。如果我编写此return(list(svalue(rep), svalue(per), svalue(car)))而不是return(list(reporter, period, vehicle))，它将返回默认值

[[1]]
[1] "write your name"

[[2]]
[1] "last month"

[[3]]
[1] "car1"

如何返回此输入值？

编辑:我对@jverzani建议的解决方案的解释如下：

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))
}

和/或：

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))
}

不幸的是，仍然是同样的问题。

Answer 1

您不能从处理程序返回值(模式对话框除外)。您需要分配它们。通常，这是通过<<-或环境完成的，因此函数体中的修改发生在函数体的范围之外。例如，在list.timeinterval处理程序中，您可以编写e$period = ...，其中e是在显示图形用户界面之前初始化的某个环境。

你的返回值会立即发生。相反，您需要将处理程序中的值分配给持久化对象。以下是一种模式：

      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))
}

当您与拨号交互时，e环境会更新。