Qshow分段错误

Question

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

我正在使用qtHaskell,但我发现跟踪示例的唯一问题是qshow分段错误.

也许有人有任何想法我怎么能尝试解决它？

谢谢.

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

补充:构建命令

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

@Foo Bah问题在12月18日被问到,我无法确定我的答案,但操作系统是Windows7,告诉我究竟能告诉我什么系统？

@Vlad Lazarenko我知道但是肯定是窗户

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

Answer 1

在您的示例中，有几个地方可能会引起麻烦。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。我会把它放在你日常工作的最后on_hello_clicked。适当的调用是returnGC. returnGC在函数末尾进行另一个调用也是一个好主意main。

其次，您的 main 函数指定了一个不存在的整数参数。您应该指定main为main :: IO ()

所以，完整的代码是：

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

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