为什么我要使用python pyqt5中从未在func中使用的参数？

Question

注:为了更好的理解，我编辑了我的问题。

我有个密码很好用。但有一件事我不太明白。

import sys

from PyQt5 import QtCore,  QtWidgets

class Ui_MainWindow(object):

    def setupUi(self, MainWindow):

        MainWindow.setObjectName("MainWindow")
        MainWindow.setWindowTitle("TEST PROGRAM")
        MainWindow.resize(1000, 700)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
        self.tabWidget = QtWidgets.QTabWidget(MainWindow)

        self.tabWidget.setGeometry(QtCore.QRect(20, 20, 1880, 950))
        self.tabWidget.setAutoFillBackground(False)
        self.tabWidget.setTabShape(QtWidgets.QTabWidget.Rounded)
        self.tabWidget.setObjectName("tabWidget")

        PreparePanel(self.tabWidget,"myPanel","TEST")

        self.tabWidget.setCurrentIndex(0)
        QtCore.QMetaObject.connectSlotsByName(MainWindow)


class PreparePanel():

    def __init__(self,twg,panelName,panelbaslik):

        self.myPanel = QtWidgets.QWidget()
        self.myPanel.setObjectName(panelName)
        twg.addTab(self.myPanel, panelbaslik)
        self.LEdit = QtWidgets.QLineEdit(self.myPanel)
        self.LEdit.setGeometry(QtCore.QRect(2, 95, 100, 22))  
        self.LEdit.setFrame(True)
        self.LEdit.setObjectName("LEdit_0")

#---------------works fine------------------------------------------------------
    #For the code to work, we need to use a dummy variable.
        self.LEdit.textChanged.connect(lambda dummyvar: self.myFilterFunc(dummyvar))

    def myFilterFunc(self,dummyVariable):
        child = self.myPanel.findChild(QtWidgets.QLineEdit, "LEdit_0")
        print(child.text())
#---------------works fine------------------------------------------------------

#--------------- does not work------------------------------------------------------
    #When we replace the above section with this section, the code does not work.
    #     
    #     self.LEdit.textChanged.connect(self.myFilterFunc)
    # def myFilterFunc(self):
    #     child = self.myPanel.findChild(QtWidgets.QLineEdit, "LEdit_0")
    #     print(child.text())


if __name__ == "__main__":
    app = QtWidgets.QApplication(sys.argv)
    pencere = QtWidgets.QWidget()
    AnaPencere = Ui_MainWindow()
    AnaPencere.setupUi(pencere)
    pencere.show()
    sys.exit(app.exec_())

我在myFilterFunc()中不使用myFilterFunc参数，但是当删除该参数时，代码无法工作并引发错误，如下所示：

AttributeError：'NoneType‘对象没有属性'text’

为什么我要放一个我从未使用过的参数？

提前谢谢。

如果将函数放在init()的开头，就不需要lambda。另外，如果我们移除PrepareClass并将PrepareClass中的代码放入Ui_MainWindow(object)类中，即使myFilterFunc()在setupUi函数之外，代码仍然工作。但我不明白为什么？

另一个有用的密码。

import sys
from PyQt5 import QtCore,  QtWidgets

class Ui_MainWindow(object):

    def setupUi(self, MainWindow):

        MainWindow.setObjectName("MainWindow")
        MainWindow.setWindowTitle("TEST")
        MainWindow.resize(1000, 700)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
        self.tabWidget = QtWidgets.QTabWidget(MainWindow)

        self.tabWidget.setGeometry(QtCore.QRect(20, 20, 1880, 950))
        self.tabWidget.setAutoFillBackground(False)
        self.tabWidget.setTabShape(QtWidgets.QTabWidget.Rounded)
        self.tabWidget.setObjectName("tabWidget")

        
        self.LEdit = QtWidgets.QLineEdit(self.tabWidget)
        self.LEdit.setGeometry(QtCore.QRect(100, 100, 150, 30))       
        self.LEdit.setFrame(True)
        self.LEdit.setObjectName("LEdit_1")

        self.LEdit.textChanged.connect(self.myFilterFunc)
        self.tabWidget.setCurrentIndex(0)
        QtCore.QMetaObject.connectSlotsByName(MainWindow)


    def myFilterFunc(self):

        child = self.tabWidget.findChild(QtWidgets.QLineEdit, "LEdit_1")
        
        print(child.text())



if __name__ == "__main__":
    app = QtWidgets.QApplication(sys.argv)
    pencere = QtWidgets.QWidget()
    AnaPencere = Ui_MainWindow()
    AnaPencere.setupUi(pencere)
    pencere.show()
    sys.exit(app.exec_())

Answer 1

首先，当你调用这个函数时，你传递的是文本。现在我并不真正理解您的代码所做的事情，因为您没有包含太多内容，但是我认为从调用中的参数中提取文本可以解决您的问题。

Answer 2

在这里，ontextchange信号无法与myfilterfunc()建立连接。因此，一个可能的解决方法是在init()中添加所有函数，并使用lambda函数向它们发送信号。

import sys

from PyQt5 import QtCore,  QtWidgets

class Ui_MainWindow(object):

    def setupUi(self, MainWindow):

        MainWindow.setObjectName("MainWindow")
        MainWindow.setWindowTitle("TEST PROGRAM")
        MainWindow.resize(1000, 700)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
        self.tabWidget = QtWidgets.QTabWidget(MainWindow)

        self.tabWidget.setGeometry(QtCore.QRect(20, 20, 1880, 950))
        self.tabWidget.setAutoFillBackground(False)
        self.tabWidget.setTabShape(QtWidgets.QTabWidget.Rounded)
        self.tabWidget.setObjectName("tabWidget")

        PreparePanel(self.tabWidget,"myPanel","TEST")

        self.tabWidget.setCurrentIndex(0)
        QtCore.QMetaObject.connectSlotsByName(MainWindow)


class PreparePanel():

    def __init__(self,twg,panelName,panelbaslik):

        self.myPanel = QtWidgets.QWidget()
        self.myPanel.setObjectName(panelName)
        twg.addTab(self.myPanel, panelbaslik)
        self.LEdit = QtWidgets.QLineEdit(self.myPanel)
        self.LEdit.setGeometry(QtCore.QRect(2, 95, 100, 22))  
        self.LEdit.setFrame(True)
        self.LEdit.setObjectName("LEdit_0")

#---------------works fine------------------------------------------------------
        self.LEdit.textChanged.connect(lambda: myFilterFunc())
        def myFilterFunc():
            child = self.myPanel.findChild(QtWidgets.QLineEdit, "LEdit_0")
            print(child.text())



if __name__ == "__main__":
    app = QtWidgets.QApplication(sys.argv)
    pencere = QtWidgets.QWidget()
    AnaPencere = Ui_MainWindow()
    AnaPencere.setupUi(pencere)
    pencere.show()
    sys.exit(app.exec_())