Question

我无法从标签和操作列表中生成按钮。我很确定这与IO没有得到评估有关（按钮上的按钮激活动作＆＃39;），但我不确定如何解决它。< / p>

我有一个（Label，Command）元组列表，我用它来生成一个Button，以及它与IO（）的关联动作。

调用的功能：＆＃39;按钮按钮激活动作＆＃39;被调用，但按钮仍然没有记录点击。

module GtkTest where

import qualified Data.Map as M
import Graphics.UI.Gtk
import Graphics.UI.Gtk.Buttons.Button
import Graphics.UI.Gtk.Windows.Window
import Graphics.UI.Gtk.Layout.VBox
import Control.DeepSeq

type Command = String
type ButtonLabel = String
type ButtonAction = IO ()
type ButtonDesc = (ButtonLabel, Command)
data ButtonInfo = ButtonInfo {
    buttonLabel :: ButtonLabel
  , buttonAction :: ButtonAction
  , buttonIo :: IO Button
  }

genAction :: Command -> ButtonAction
genAction command = putStrLn ("Running: " ++ command)

genButton :: ButtonDesc -> ButtonInfo
genButton info = let (label, command) = info
                 in ButtonInfo label (genAction command) (buttonNewWithLabel label)

getButtonDescs :: IO [ButtonDesc]
getButtonDescs = return [("Ok", "ok"),
                         ("Foo", "foo"),
                         ("Bar", "bar")]

applyAction (ButtonInfo _ action io) = do
--This gets called
  putStrLn "applying click handler"
  button <- io
--But apparently not this
  on button buttonActivated action

addIoToContainer container io = do
  widget <- io
  containerAdd container widget

main = do
  initGUI
  window <- windowNew
--These buttons do not work
  buttonDescs <- getButtonDescs
  buttons <- return $ map genButton buttonDescs
  vbox <- vBoxNew True 0
  _ <- sequence $ map ((addIoToContainer vbox) . buttonIo) buttons
  _ <- sequence $ map applyAction buttons
  _ <- containerAdd window vbox
-- This button works
  button <- buttonNewWithLabel "Manually made"
  on button buttonActivated $ genAction "Manual action"
  containerAdd vbox button
  onDestroy window mainQuit
  widgetShowAll window
  mainGUI

非常感谢任何帮助。谢谢。

编辑：

根据chi的回答，我将ButtonInfo数据类型更新为不执行IO，最后使用IO [ButtonInfo]，这允许我绑定操作。

修订来源（工作）：

module GtkTest where

import qualified Data.Map as M
import Graphics.UI.Gtk
import Graphics.UI.Gtk.Buttons.Button
import Graphics.UI.Gtk.Windows.Window
import Graphics.UI.Gtk.Layout.VBox
import Control.DeepSeq

type Command = String
type ButtonLabel = String
type ButtonAction = IO ()
type ButtonDesc = (ButtonLabel, Command)
data ButtonInfo = ButtonInfo {
    buttonLabel :: ButtonLabel
  , buttonAction :: ButtonAction
  , buttonWidget :: Button
  }

genAction :: Command -> ButtonAction
genAction command = putStrLn ("Running: " ++ command)

genButton :: ButtonDesc -> IO ButtonInfo
genButton info = let (label, command) = info
                 in do
                   button <- (buttonNewWithLabel label)
                   return $ ButtonInfo label (genAction command) button

getButtonDescs :: IO [ButtonDesc]
getButtonDescs = return [("Ok", "ok"),
                         ("Foo", "foo"),
                         ("Bar", "bar")]

applyAction (ButtonInfo _ action widget) = do
  putStrLn "applying click handler"
  on widget buttonActivated action

addIoToContainer container io = do
  widget <- io
  containerAdd container widget

main = do
  initGUI
  window <- windowNew
  buttonDescs <- getButtonDescs
  buttons <- sequence $ map genButton buttonDescs
  vbox <- vBoxNew True 0
  _ <- sequence $ map ((containerAdd vbox) . buttonWidget) buttons
  _ <- sequence $ map applyAction buttons
  _ <- containerAdd window vbox
  button <- buttonNewWithLabel "Manually made"
  on button buttonActivated $ genAction "Manual action"
  containerAdd vbox button
  onDestroy window mainQuit
  widgetShowAll window
  mainGUI

Answer 1

我可以看到，buttonIo的{{1}}字段存储了一个动作，每次运行时都会创建一个新按钮。因此，代码

ButtonInfo

看起来不对，因为applyAction (ButtonInfo _ action io) = do putStrLn "applying click handler" button <- io -- (1) on button buttonActivated action addIoToContainer container io = do widget <- io -- (2) containerAdd container widget创建了一个新按钮（行addIoToContainer）并将其添加到容器中，而(2)创建了另一个按钮（行applyAction）并带有{ {1}}附加行动。因此，屏幕上会显示一个无响应的按钮，屏幕上会显示一个响应按钮。

我的建议是使用

(1)

由于buttonActivated和data ButtonInfo = ButtonInfo { buttonLabel :: ButtonLabel , buttonAction :: ButtonAction , buttonIo :: Button -- no IO here! }属于不同类型，这会立即导致很多类型错误。这很好，因为修复这些类型的错误会迫使你只创建一次按钮，这样就可以让它们响应并在屏幕上显示。

Haskell＆amp; gtk2hs，按钮激活信号无法绑定

1 个答案: