[PyQt] using itemDoubleClicked with pyqt

[Mark Summerfield]

Hi Chris,

On 2010-06-23, Christopher M. Nahler wrote:
> On 23.06.2010 09:46, Phil Thompson wrote:
> >  On Wed, 23 Jun 2010 09:40:09 +0200, "Christopher M. Nahler"
[snip]
> >  The signal signature is "itemDoubleClicked(QListWidgetItem *)"
> >  
> >  Phil
> 
> The way I understand this is that the signal passes a pointer to an
> item, right? So what is the correct way to setup the connection? I have
> tried with SIGNAL("itemDoubleClicked(item*)" and
> SIGNAL("itemDoubleClicked(item *)" but that also did not work.

The thing about using Qt signals is that you must specify the signal's
_signature_, i.e., the type(s) it takes, but not their parameter names.
This is a bit counter-intuitive for Python programmers since we're used
to using parameter names not types.

So,

    self.connect(self.myList,
		 SIGNAL("itemDoubleClicked(*item)"), # WRONG
		 self.processItem)

must be written as:

    self.connect(self.myList,
		 SIGNAL("itemDoubleClicked(QListWidgetItem*)"),
		 self.processItem)

The quoted string inside SIGNAL must be the name of the signal and its
parameter _types_. So for example, if you want to know when the current
row has changed you'd write (assuming that self.myList is a QListWidget):

    self.connect(self.myList,
	SIGNAL("currentItemChanged(QListWidgetItem*,QListWidgetItem*)"),
	self.currentChanged)

and the currentChanged method would look like this:

    def currentChanged(self, currentListItem, previousListItem):
	pass

Hope that helps:-)

-- 
Mark Summerfield, Qtrac Ltd, www.qtrac.eu
    C++, Python, Qt, PyQt - training and consultancy
        "Advanced Qt Programming" - ISBN 0321635906
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