qt - Qshow段错误

Question

  setText mb $ "Hello World"
  qshow mb () -- Segmentation Failt 
  --print ("Hello world") -- it works

我正在使用 qtHaskell，但我在这里发现跟踪示例的唯一问题是 qshow 段错误。

也许有人有任何想法我该如何解决？

谢谢你。

补充:完整的程序代码:

module Main where

import Qtc.Classes.Qccs
import Qtc.Classes.Gui
import Qtc.ClassTypes.Gui
import Qtc.Core.Base
import Qtc.Gui.Base
import Qtc.Gui.QApplication
import Qtc.Gui.QWidget
import Qtc.Gui.QPushButton
import Qtc.Gui.QAbstractButton
import Qtc.Gui.QMessageBox

type MyQPushButton = QPushButtonSc (CMyQPushButton)
data CMyQPushButton = CMyQPushButton

myQPushButton :: String -> IO (MyQPushButton)
myQPushButton b = qSubClass $ qPushButton b

main :: IO Int
main = do
  qApplication ()
  hello <- myQPushButton "Hello qtHaskell World"
  resize hello (200::Int, 60::Int)
  mb <- qMessageBox hello 
  connectSlot hello "clicked()" hello "click()" $ on_hello_clicked mb
  qshow hello ()
  qApplicationExec ()

on_hello_clicked :: QMessageBox () -> MyQPushButton -> IO ()
on_hello_clicked mb this
  = do
  tt <- text this ()
  setText mb $ "You have clicked " ++ tt
  qshow mb ()

添加了 valgrind 日志

> > ncdy@Cndy ~/Haskell $ valgrind ./a
> ==13467== Memcheck, a memory error detector
> ==13467== Copyright (C) 2002-2010, and GNU GPL'd, by Julian Seward et al.
> ==13467== Using Valgrind-3.6.0 and LibVEX; rerun with -h for copyright
> info
> ==13467== Command: ./a
> ==13467== 
> 
> ==13467== Syscall param writev(vector[...]) points to
> uninitialised byte(s)
> ==13467==    at 0x40008D2: ??? (in /lib/ld-2.11.2.so)
> ==13467==  Address 0x6e85d97 is 2,703 bytes inside a block of size 16,384
> alloc'd
> ==13467==    at 0x4027834: calloc (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
> ==13467==    by 0x69C4BD4: XOpenDisplay (in
> /usr/lib/libX11.so.6.3.0)
> ==13467==    by 0x4C505F53: ???
> ==13467== 
> ==13467== 
> ==13467== Process terminating with default action of signal 11 (SIGSEGV)
> ==13467==  General Protection Fault
> ==13467==    at 0x5957480: ??? (in /usr/lib/qt4/libQtGui.so.4.7.1)
> ==13467==    by 0x5B5FD81: ??? (in /usr/lib/qt4/libQtGui.so.4.7.1)
> ==13467==    by 0x5B6BC19: ??? (in /usr/lib/qt4/libQtGui.so.4.7.1)
> ==13467==    by 0x5B71B3C: ??? (in /usr/lib/qt4/libQtGui.so.4.7.1)
> ==13467==    by 0x5AE757D: QPainter::drawPixmap(QRectF const&,
> QPixmap const&, QRectF const&) (in
> /usr/lib/qt4/libQtGui.so.4.7.1)
> ==13467==    by 0xA71AA68: Oxygen::Helper::renderWindowBackground(QPainter*,
> QRect const&, QWidget const*, QWidget
> const*, QColor const&, int, int) (in
> /usr/lib/liboxygenstyle.so.4.5.0)
> ==13467== Invalid free() / delete / delete[]
> ==13467==    at 0x402868B: free (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
> ==13467==    by 0x52F78DB: ??? (in /lib/libc-2.11.2.so)
> ==13467==    by 0x105FFFF: ???
> ==13467==  Address 0x5133a98 is not stack'd, malloc'd or (recently) free'd
> ==13467== 
> ==13467== 
> ==13467== HEAP SUMMARY:
> ==13467==     in use at exit: 1,968,209 bytes in 27,864 blocks
> ==13467==   total heap usage: 65,595 allocs, 37,732 frees, 6,175,162 bytes
> allocated
> ==13467== 
> ==13467== LEAK SUMMARY:
> ==13467==    definitely lost: 18,054 bytes in 259 blocks
> ==13467==    indirectly lost: 94,591 bytes in 628 blocks
> ==13467==      possibly lost: 489,039 bytes in 5,656 blocks
> ==13467==    still reachable: 1,366,525 bytes in 21,321 blocks
> ==13467==         suppressed: 0 bytes in 0 blocks
> ==13467== Rerun with --leak-check=full to see details of leaked memory
> ==13467== 
> ==13467== For counts of detected and suppressed errors, rerun with: -v
> ==13467== Use --track-origins=yes to see where uninitialised values come
> from
> ==13467== ERROR SUMMARY: 3 errors from 2 contexts (suppressed: 15 from 8)
> Segmentation fault

添加:构建命令

ghc --make -package qt -fglasgow-exts -O2 -o a HCK.hs -i

@Foo Bah 这个问题是在 12 月 18 日提出的，我不能确定我的答案，但操作系统是 Windows7，告诉我我能告诉我关于系统的确切信息吗？

@Vlad Lazarenko 我知道，但肯定是 window )

@Foo Bah 使用cygwin，是吗？我需要在哪里使用它？我在这台机器上，我可以再次尝试 qtHaskell 并检查当前情况，但我想会有另一个版本。

Answer 1

在您的示例中，有几个地方可能会造成麻烦。我在这里强调可能是因为处理内存问题可能非常依赖于您使用哪个库进行内存管理。

首先，您需要在垃圾收集应该运行时通知 qtHaskell。我会把它放在你的 on_hello_clicked 的末尾常规。合适的电话是returnGC .放置另一个 returnGC 也是一个好主意在您的 main 结束时调用功能。

其次，您的主要功能是指定一个不存在的整数参数。您应该指定 main如main :: IO ()
因此，完整的代码将是:

module Main where

import Qtc.Classes.Qccs
import Qtc.Classes.Gui
import Qtc.ClassTypes.Gui
import Qtc.Core.Base
import Qtc.Gui.Base
import Qtc.Gui.QApplication
import Qtc.Gui.QWidget
import Qtc.Gui.QPushButton
import Qtc.Gui.QAbstractButton
import Qtc.Gui.QMessageBox

type MyQPushButton = QPushButtonSc (CMyQPushButton)
data CMyQPushButton = CMyQPushButton

myQPushButton :: String -> IO (MyQPushButton)
myQPushButton b = qSubClass $ qPushButton b

main :: IO ()
main = do
  qApplication ()
  hello <- myQPushButton "Hello qtHaskell World"
  resize hello (200::Int, 60::Int)
  mb <- qMessageBox hello 
  connectSlot hello "clicked()" hello "click()" $ on_hello_clicked mb
  qshow hello ()
  qApplicationExec ()
  returnGC

on_hello_clicked :: QMessageBox () -> MyQPushButton -> IO ()
on_hello_clicked mb this
  = do
  tt <- text this ()
  setText mb $ "You have clicked " ++ tt
  qshow mb ()
  returnGC

这可以在 WindowsXP + Cygwin 以及 MacOS 10.6 上很好地编译和运行