Question

我想从PyQt脚本中捕获stderr输出并将其显示在QMessageBox中。我找到了这些帖子并尝试了它们，但没有一个对我有效：

我遇到了一些问题。首先，单个错误似乎是作为一系列单独的stderr消息发送的（至少在Python 3.4中）。这导致使用我找到的方法打开多个消息框，并且需要使用.show()而不是.exec()并将单独的消息累积到一个消息框中。

此外，如果发生第二个错误，即使第一个消息框已关闭，第一个错误中的文本仍保留在新消息框中。我尝试拨打.destroy()并使用Qt.WA_DeleteOnClose，但第一个消息框实际上并没有消失。所以我最终只是删除了持久性消息框中的文本。

找到一个干净的方式来同时关闭＆＃39;关闭窗口＆＃39;并且＆＃39;好的＆＃39;事件也进行了一些实验。

Answer 1

我找到了一些似乎能完成这项工作的东西，就像我能做到的那样简单。如果有人有改进或可以解释我在这里工作的问题，请编辑代码。

这是一个示例，它启动一个简单的主窗口，其中包含一个用于创建stderr的按钮。将捕获错误消息并将其显示在消息框中，该消息框可以正确清除＆＃39;确定＆＃39;或关闭。该技术也可以与stdout一起使用。

from PyQt4 import QtGui

class StdErrHandler():
    def __init__(self):
        # To instantiate only one message box
        self.err_box = None

    def write(self, std_msg):
        # All that stderr or stdout require is a class with a 'write' method.
        if self.err_box is None:
            self.err_box = QtGui.QMessageBox()
            # Both OK and window delete fire the 'finished' signal
            self.err_box.finished.connect(self.clear)
        # A single error is sent as a string of separate stderr .write() messages, 
        # so concatenate them.
        self.err_box.setText(self.err_box.text() + std_msg)
        # .show() is used here because .exec() or .exec_() create multiple
        # MessageBoxes.
        self.err_box.show()

    def clear(self):
        # QMessageBox doesn't seem to be actually destroyed when closed, just hidden.
        # This is true even if destroy() is called or if the Qt.WA_DeleteOnClose 
        # attribute is set.  Clear text for next time.
        self.err_box.setText('')

class AppMainWindow(QtGui.QMainWindow):
    """
    Main window with button to create an error
    """
    def __init__(self, parent=None):
        # initialization of the superclass
        super(AppMainWindow, self).__init__(parent)

        self.create_err = QtGui.QPushButton(self)
        self.create_err.setText("Create Error")
        self.create_err.clicked.connect(self.err_btn_clicked)

    def err_btn_clicked(self):
        # Deliberately create a stderr output
        oopsie

if __name__ == "__main__":
    import sys

    app = QtGui.QApplication(sys.argv)
    amw = AppMainWindow()
    amw.show()

    # Instantiate stderr handler class
    std_err_handler = StdErrHandler()
    # Connect stderr to the handler
    sys.stderr = std_err_handler
    sys.exit(app.exec_())

修改正如three_pineapples指出的那样，这不是线程安全的。我发现当我在另一个应用程序中安装此消息时，如果在pydev调试器下运行应用程序时出现stderr，则消息框将挂起，这可能是由于此原因。

我使用线程和队列重写了它，但这也挂了。

然后我了解到PyQt信号和＆amp;插槽是线程安全的，所以我只用它重写了它。下面的版本是线程安全的（我认为）并作为独立脚本或在调试器下正确运行：

from PyQt4 import QtCore, QtGui class StdErrHandler(QtCore.QObject): ''' This class provides an alternate write() method for stderr messages. Messages are sent by pyqtSignal to the pyqtSlot in the main window. ''' err_msg = QtCore.pyqtSignal(str) def __init__(self, parent=None): QtCore.QObject.__init__(self) def write(self, msg): # stderr messages are sent to this method. self.err_msg.emit(msg) class AppMainWindow(QtGui.QMainWindow): ''' Main window with button to create an error ''' def __init__(self, parent=None): # initialization of the superclass super(AppMainWindow, self).__init__(parent) # To avoid creating multiple error boxes self.err_box = None # Single button, connect to button handler self.create_err = QtGui.QPushButton(self) self.create_err.setText("Create Error") self.create_err.clicked.connect(self.err_btn_clicked) def err_btn_clicked(self): # Deliberately create a stderr output oopsie def std_err_post(self, msg): ''' This method receives stderr text strings as a pyqtSlot. ''' if self.err_box is None: self.err_box = QtGui.QMessageBox() # Both OK and window delete fire the 'finished' signal self.err_box.finished.connect(self.clear) # A single error is sent as a string of separate stderr .write() messages, # so concatenate them. self.err_box.setText(self.err_box.text() + msg) # .show() is used here because .exec() or .exec_() create multiple # MessageBoxes. self.err_box.show() def clear(self): # QMessageBox doesn't seem to be actually destroyed when closed, just hidden. # This is true even if destroy() is called or if the Qt.WA_DeleteOnClose # attribute is set. Clear text for next time. self.err_box.setText('') if __name__ == '__main__': import sys app = QtGui.QApplication(sys.argv) amw = AppMainWindow() amw.show() # Create the stderr handler and point stderr to it std_err_handler = StdErrHandler() sys.stderr = std_err_handler # Connect err_msg signal to message box method in main window std_err_handler.err_msg.connect(amw.std_err_post) sys.exit(app.exec_())

在pyqt QMessageBox中显示stderr

1 个答案: