Re: Overloading virtual method of widget without inheriting (PyQt)

Collapse
This topic is closed.
X
X
 
  • Time
  • Show
Clear All
new posts
  • David Boddie

    Re: Overloading virtual method of widget without inheriting (PyQt)

    On Mon May 26 17:37:04 CEST 2008, Alex Gusarov wrote:
    Hello, I have strong .NET background with C# and want to do some familiar
    things from it with Python, but don't know how. For example, I created form
    in qt designer with QCalendarWidget , translated it into Python module and
    want to overload virtual method paintCell of QCalendarWidget . In C# I can
    write following (abstract) code:
    >
    this.calendar.P aintCell += new PaintEventHandl er(myPaintCellH andler);
    >
    void myPaintCellHand ler(object sender, PaintEventArgs e) {
    // some work here
    }
    Right. I vaguely remember someone showing something like this at EuroPython
    a couple of years ago. I believe that this approach is actually registering
    an event handler (or callback) to handle a certain type of event.
    I can't find how I can do similar thing in Python without inheriting
    QCalendarWidget and overloading this method in inherited class (it's long
    and I must create additional class).
    Just out of interest, given that you have to put the event handler somewhere,
    why is it a problem to derive a new class and reimplement paintCell()?

    It really isn't that much code:

    class MyCalendarWidge t(QCalendarWidg et):

    def paintCell(self, painter, rect, date):
    # some work here
    So, I need to run my code whenever paintCell is called by Qt internals and
    I have no enough experience with Python for it. Please, give me some
    advice, I know Python must be good enough to do such things.
    The principal mechanism for doing this is via inheritance. You can do things
    with event filters, but it's more complex and almost like working against the
    design of the library to do so.

    I have a feeling that the form produced by Qt Designer, once converted to
    code, contains references to QCalendarWidget where you really want to use a
    customized calendar widget. If so, you should "promote" the calendar widget
    in Qt Designer to use your widget instead, and make sure you import the
    module that supplies it in your application.

    If you need more information about this, just ask.

    David
    --
    David Boddie
    Lead Technical Writer, Trolltech ASA
Working...