What is this code from createEditor actually doing (Rapid Gui Programming With Python and Qt)

Question

I'm going through "Rapid Gui Programming With Python and Qt". In chapter 14, we implement our own delegate class. One of the functions is called createEditor. Here's the code for it:

def createEditor(self, parent, option, index):
    if index.column() == TEU:
        spinbox = QSpinBox(parent)
        spinbox.setRange(0, 200000)
        spinbox.setSingleStep(1000)
        spinbox.setAlignment(Qt.AlignRight|Qt.AlignVCenter)
        return spinbox
    elif index.column() == OWNER:
        combobox = QComboBox(parent)
        combobox.addItems(sorted(index.model().owners))
        combobox.setEditable(True)
        return combobox
    elif index.column() == COUNTRY:
        combobox = QComboBox(parent)
        combobox.addItems(sorted(index.model().countries))
        combobox.setEditable(True)
        return combobox
    elif index.column() == NAME:
        editor = QLineEdit(parent)
        self.connect(editor, SIGNAL("returnPressed()"),
                     self.commitAndCloseEditor)
        return editor
    elif index.column() == DESCRIPTION:
        editor = richtextlineedit.RichTextLineEdit(parent)
        self.connect(editor, SIGNAL("returnPressed()"),
                     self.commitAndCloseEditor)
        return editor
    else:
        return QStyledItemDelegate.createEditor(self, parent, option,
                                                index)

Here's the code for commitAndCloseEditor:

def commitAndCloseEditor(self):
    editor = self.sender()
    if isinstance(editor, (QTextEdit, QLineEdit)):
        self.emit(SIGNAL("commitData(QWidget*)"), editor)
        self.emit(SIGNAL("closeEditor(QWidget*)"), editor)

I understand what's happening for the TEU, OWNER, COUNTRY and DESCRIPTION columns. However, I don't see what's being achieved in the NAME column. In fact, I commented the NAME code out so the base function would be called and I can't see any difference whatsoever...

Answer 1

self.connect(editor, SIGNAL("returnPressed()"),
                 self.commitAndCloseEditor)

What that line does is call Qt's connect function to create a link between a SIGNAL , which in this case is returnPressed , and a SLOT which is a function and in this case is the commitAndCloseEditor . Without digging into the code too much it looks like it's there so when the return key is pressed and commitAndCloseEditor function is triggered to update the data source and close an editor view for the table.