[PyQt] Custom Widgets and __pyqtSignals__

[Marco Fabiani]

Marco Fabiani wrote:
> David Boddie wrote:
>> On Sun Aug 24 12:43:33 BST 2008, Paul Giannaros wrote:
>>> On Sun, Aug 24, 2008 at 12:03 PM, himork <himork at kth.se> wrote:
>>>> I am trying to write a custom widget in python/pyqt to be used inside
>>>> QtDesigner. Everything seems to work fine (i followed the tutorials and
>>>> examples available), except for the signals: when I use __pyqtSignals__ =
>>>> ("mysignal(double)"), the widget ends up having one signal for each
>>>> letter of "mysignal(double)", parenthesis included, like it cannot
>>>> understand that this is a string.
>> Paul's explanation is correct. This is an interesting side effect of the
>> fact that PyQt accepts any kind of sequence for __pyqtSignals__.
> 
> The comma worked, thank you!
> 
>>>> And if I had 2 signals, designer crashes when I try to add my custom
>>>> widget.
>> Can you say what you wrote for __pyqtSignals__ in that case? I would be
>> interested to know why it caused a crash.

A follow up to my previous email: the code I posted didn't crash because 
it was not doing what it was meant to do. What I am trying to do is to 
subclass QSlider in order to emit a custom signal 
valueDoubleChanged(double) that is just value/100. Here is my code that 
crashes designer, I wonder if you could give me a hand with this:

----------
from PyQt4.QtCore import *
from PyQt4.QtGui import *

class myDoubleSlider(QSlider):

	__pyqtSignals__ = ("valueDoubleChanged(double)",)
	
	def __init__(self,parent = None):
	
		QSlider.__init__(self,parent)
		self.setOrientation(Qt.Horizontal)
		self.connect( self , SIGNAL("valueChanged(int)") , self.setValueDouble)	

	@pyqtSignature("setValueDouble(double)")
	def setValueDouble(self):
		self.emit(SIGNAL("valueDoubleChanged(double)") , self.value()/100)
		
		
if __name__ == "__main__":

     import sys

     app = QApplication(sys.argv)
     slider = myDoubleSlider()
     slider.show()
     sys.exit(app.exec_())	

-----

Thank you
Marco

> 
> The crash happens when I pass __pyqtSignal__ a tuple (so it happened
> with the single signal + comma as well). Here is part of the code:
> 
> [...]
> 
> __pyqtSignal = ("valueDChanged(double)",)
> 
> [...]
>         @QtCore.pyqtSignature("setValueDouble(double)")
>         def setValueDouble(self, value = None):
>                 if value !=self.valueD:
>                         if value is not None:
>                                 self.valueD = value
>                         self.setValue(int(round(self.valueD*100)))
>                 seelf.emit(QtCore.SIGNAL("valueDChanged(double)"),value)
>                         self.update()
> [...]
> 
> 
> I managed not to crash designer by using self.valueD instead of value
> when I emit the signal. My guess is that the problem is "value" that by
> default is "None", am I right?
> 
> Thanks for the help!
> Marco
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