Connect the right Button with the right Table

Question

I have a problem with the creation of multiple tabs in table and a delete button. This button should delete the rows in the current table. My problem is that it only deletes rows in the last created table if I create more than one new tab. And I can't name the tables due to the fact that I don't know how many tabs I need.

import sys
from PyQt4 import QtGui, QtCore

class Fenster(QtGui.QMainWindow):

    def __init__(self, parent=None):

        QtGui.QMainWindow.__init__(self, parent)

        self.resize(300, 300)

        addButton = QtGui.QPushButton(u"Add Tab")
        self.connect(addButton, QtCore.SIGNAL("clicked()"), self.addTab)

        layout = QtGui.QVBoxLayout()
        layout.addWidget(addButton)

        self.tab_widget = QtGui.QTabWidget()
        self.tab_widget.updatesEnabled()
        widget = QtGui.QWidget()
        self.tab_widget.addTab(widget, "Tab 1")
        widget.setLayout(layout)

        self.setCentralWidget(self.tab_widget)
        self.show()


    def addTab(self):

        contents = QtGui.QWidget()

        delButton = QtGui.QPushButton(u"Del Row")
        self.connect(delButton, QtCore.SIGNAL("clicked()"), self.delRow)

        self.table = QtGui.QTableWidget(5, 2)

        layout = QtGui.QVBoxLayout()
        layout.addWidget(self.table)
        layout.addWidget(delButton)

        self.tab_widget.addTab(contents, "New Tab")

        contents.setLayout(layout)

    def delRow(self):

        self.table.setRowCount(0)        

if __name__ == '__main__':
    app = QtGui.QApplication(sys.argv)
    window = Fenster()
    window.show()
    sys.exit(app.exec_())        

Answer 1

The problem is that self.table always points to the last table widget you created. The delRow method needs to know which table to delete from, so it needs a reference to that table. I would suggest the following code. Here, your slot takes an argument that points to the table you want to delete from.

def addTab(self):

    contents = QtGui.QWidget()

    table = QtGui.QTableWidget(5, 2)
    delButton = QtGui.QPushButton(u"Del Row")
    delButton.clicked.connect(lambda: self.delRow(table))


    layout = QtGui.QVBoxLayout()
    layout.addWidget(table)
    layout.addWidget(delButton)

    self.tab_widget.addTab(contents, "New Tab")

    contents.setLayout(layout)

def delRow(self, table):

    table.setRowCount(0) 

A couple of things about this code:

• I've used the new style signal/slot method to connect the clicked signal to a slot (it is more pythonic)

• Because the signal expects to connect to a slot that takes no arguments, I've wrapped your delRow(table) method using lambda. If you haven't come across lambda before, it is basically short hand for writing a one line function. You can read up about it in the Python docs.

Answer 2

You could track which tab is active via currentChanged() signal. Then in signal handler you set self.table.