[PyQt] Subclassing QNetworkReply

[Detlev Offenbach]

On Montag, 2. März 2009, Phil Thompson wrote:
> On Mon, 2 Mar 2009 18:33:01 +0100, Detlev Offenbach
>
> <detlev at die-offenbachs.de> wrote:
> > On Montag, 2. März 2009, Phil Thompson wrote:
> >> On Mon, 2 Mar 2009 18:19:57 +0100, Detlev Offenbach
> >>
> >> <detlev at die-offenbachs.de> wrote:
> >> > Hi,
> >> >
> >> > I am trying to write a subclass of QNetworkReply. This subclass needs
> >> > to
> >> > have
> >> > it's own variant of the readData protected method. However, it seems,
> >>
> >> that
> >>
> >> > this method doesn't work correctly. How do I have to do this
>
> correctly.
>
> >> My
> >>
> >> > code is shown below.
> >> >
> >> > --------------
> >> > class HelpNetworkReply(QNetworkReply):
> >> >     def __init__(self, request, fileData):
> >> >         QNetworkReply.__init__(self)
> >> >
> >> >         self.__data = QBuffer(fileData)
> >> >
> >> >         self.setRequest(request)
> >> >         self.setOpenMode(QIODevice.ReadOnly)
> >> >
> >> >         self.setHeader(QNetworkRequest.ContentTypeHeader,
> >> > 		       QVariant("text/html"))
> >> >         self.setHeader(QNetworkRequest.ContentLengthHeader,
> >> >                        QVariant(QByteArray.number(fileData.length())))
> >> >         QTimer.singleShot(0, self, SIGNAL("metaDataChanged()"))
> >> >         QTimer.singleShot(0, self, SIGNAL("readyRead()"))
> >> >
> >> >     def abort(self):
> >> >         # do nothing
> >> >         pass
> >> >
> >> >     def readData(self, buffer, maxlen):
> >> >         l = self.__data.readData(buffer, maxlen)
> >> >         if self.__data.bytesAvailable() == 0:
> >> >             QTimer.singleShot(0, self, SIGNAL("finished()"))
> >> >         return l
> >> > --------------
> >>
> >> The Python signature is slightly different as Python strings aren't
> >> mutable. There is no buffer argument and you should return the data as a
> >> Python string.
> >>
> >> Phil
> >> _______________________________________________
> >> PyQt mailing list    PyQt at riverbankcomputing.com
> >> http://www.riverbankcomputing.com/mailman/listinfo/pyqt
> >
> > So I have to "return l, buffer" with buffer being a Python string.
>
> No, just buffer. The handwritten code for readData() gets the length from
> the buffer.

That works now. However, I am facing a new problem. After several requests 
with a "qthelp" scheme, my application is crashing with a segfault. If I keep 
the references to the reply objects (i.e. never clean the array), it works 
(but leaks memory). What is wrong?

Note: engine is a reference to a QHelpEngine object.

---------------
class HelpNetworkAccessManager(QNetworkAccessManager):
    def __init__(self, engine, parent = None):
        QNetworkAccessManager.__init__(self, parent)
        
        self.__engine = engine
        self.__helpreplies = []
    
    def createRequest(self, op, request, outgoingData):
        for reply in self.__helpreplies[:]:
            if reply.isFinished():
                self.__helpreplies.remove(reply)
                del reply
        
        scheme = request.url().scheme()
        if scheme == "qthelp":
            reply = HelpNetworkReply(request, 
		                     self.__engine.fileData(request.url()))
            self.__helpreplies.append(reply)
            print len(self.__helpreplies)
            return reply
        
        return QNetworkAccessManager.createRequest(self, op, request, 
						   outgoingData)
---------------

Regards,
Detlev
-- 
Detlev Offenbach
detlev at die-offenbachs.de