将PySide应用程序设置为QScrollArea时会崩溃

Question

这是对我编写的应用程序的简化。

该应用程序的主窗口有一个按钮和一个复选框。 该复选框位于QScrollArea内部（通过小部件）。 该复选框有一个数字，表明该复选框已创建多少次。 点击按钮将打开一个带有刷新按钮的对话框。

点击刷新按钮将设置一个新的窗口小部件到一个新的复选框。

该复选框的上下文菜单打开了相同的对话框。 然而，使用复选框的上下文菜单中触发该对话框中创建窗口小部件时，出现以下错误的应用程序崩溃：

2016-08-03 09:22:00.036 Python[17690:408202] modalSession has been exited prematurely - check for a reentrant call to endModalSession:

Python(17690,0x7fff76dcb300) malloc: * error for object 0x7fff5fbfe2c0: pointer being freed was not allocated * set a breakpoint in malloc_error_break to debug

的崩溃不会在按钮上单击打开对话框出现时并点击对话框中的刷新。

崩溃发生在Mac和Windows上。 我使用Python 2.7.10与PySide 1.2.4

#!/usr/bin/env python 
import sys 
from itertools import count 
from PySide import QtCore, QtGui 

class MainWindow(QtGui.QMainWindow): 
    def __init__(self, *args, **kwargs): 
     super(MainWindow, self).__init__(*args, **kwargs) 
     self.centralwidget = QtGui.QWidget(parent=self) 

     self.open_diag_btn = QtGui.QPushButton('Open dialog', parent=self) 
     self.open_diag_btn.clicked.connect(self.open_dialog) 
     self.scroll_widget = QtGui.QScrollArea(parent=self) 

     layout = QtGui.QGridLayout(self.centralwidget) 
     layout.addWidget(self.scroll_widget) 
     layout.addWidget(self.open_diag_btn) 
     self.setCentralWidget(self.centralwidget) 
     self.set_scroll_widget() 

    def open_dialog(self): 
     dialog = Dialog(parent=self) 
     dialog.refresh.connect(self.set_scroll_widget) # Connecting the signal from the dialog to set a new widget to the scroll area 
     dialog.exec_() 
     # Even if I call the function here, after the dialog was closed instead of using the signal above the application crashes, but only via the checkbox 
     # self.set_scroll_widget() 

    def set_scroll_widget(self): 
     """Replacing the widget of the scroll area with a new one. 
      The checkbox in the layout of the widget has an class instance counter so you can see how many times the checkbox was created.""" 
     widget = QtGui.QWidget() 
     layout = QtGui.QVBoxLayout(widget) 
     widget.setLayout(layout) 
     open_diag_check = RefreshCheckbox(parent=self) 
     open_diag_check.do_open_dialog.connect(self.open_dialog) # Connecting the signal to open the dialog window 

     layout.addWidget(open_diag_check) 
     self.scroll_widget.setWidget(widget) 


class RefreshCheckbox(QtGui.QCheckBox): 
    """A checkbox class that has a context menu item which emits a signal that eventually opens a dialog window""" 
    do_open_dialog = QtCore.Signal() 
    _instance_counter = count(1) 

    def __init__(self, *args, **kwargs): 
     super(RefreshCheckbox, self).__init__(unicode(self._instance_counter.next()), *args, **kwargs) 
     self.setContextMenuPolicy(QtCore.Qt.ActionsContextMenu) 
     action = QtGui.QAction(self) 
     action.setText("Open dialog") 
     action.triggered.connect(self.emit_open_dialog) 
     self.addAction(action) 

    def emit_open_dialog(self): 
     self.do_open_dialog.emit() 


class Dialog(QtGui.QDialog): 
    """A dialog window with a button that emits a refresh signal when clicked. 
     This signal is used to call MainWindow.set_scroll_widget()""" 
    refresh = QtCore.Signal() 

    def __init__(self, *args, **kwargs): 
     super(Dialog, self).__init__(*args, **kwargs) 
     self.refresh_btn = QtGui.QPushButton('Refresh') 
     self.refresh_btn.clicked.connect(self.do_refresh) 
     layout = QtGui.QVBoxLayout(self) 
     layout.addWidget(self.refresh_btn) 

    def do_refresh(self): 
     self.refresh.emit() 


if __name__ == "__main__": 
    app = QtGui.QApplication(sys.argv) 
    mySW = MainWindow() 
    mySW.show() 
    mySW.raise_() 
    app.exec_() 

Answer 1

它看起来像Python是试图删除一个对象（或子对象之一），后者不再有 - 但是导致这种情况发生的原因并不完全清楚。有问题的对象是在滚动区域上设置的小部件。如果您明确地保留对它的引用：

def set_scroll_widget(self): 
     self._old_widget = self.scroll_widget.takeWidget() 
     ... 

您的示例将不再转储核心。

我认为运行对话框exec可能在某种程度上是问题的近端原因，因为这意味着它将运行自己的事件循环（这可能会影响删除相关事件的顺序）。我能够用show运行对话框中找到你的例子更好的解决办法：

def open_dialog(self): 
    dialog = Dialog(parent=self) 
    dialog.setAttribute(QtCore.Qt.WA_DeleteOnClose) 
    dialog.refresh.connect(self.set_scroll_widget) 
    dialog.setModal(True) 
    dialog.show() 

处事这样意味着它不再需要保持一个明确的参照以前的滚动区域部件。