yes It has instance of both Reporter and Switch.
moreover I could not get why instance "reporter" is passed to class Switch
as a parameter ?
> > reporter = Reporter()
> > switch = Switch(0,reporter)
> > switch(1)
thanks
On Thursday, June 18, 2015 at 5:45:08 PM UTC+5:30, MRAB wrote:
> On 2015-06-18 08:41, ravi wrote:
> > hi,
> > I am new to python and need to know why the calling of switch(1) invokes
> > the function "listen" twice in the below program?
> >
> >
> >
> > import stackless
> >
> > class EventHandler:
> > def __init__(self,*outputs):
> > if outputs==None:
> > self.outputs=[]
> > else:
> > self.outputs=list(outputs)
> >
> > self.channel = stackless.channel()
> > stackless.tasklet(self.listen)()
> >
> > def listen(self):
> > print "in listen()..."
> > while 1:
> > val = self.channel.receive()
> > self.processMessage(val)
> > for output in self.outputs:
> > self.notify(output)
> >
> > def processMessage(self,val):
> > pass
> >
> > def notify(self,output):
> > pass
> >
> > def registerOutput(self,output):
> > print "in registerOutput()..."
> > self.outputs.append(output)
> >
> > def __call__(self,val):
> > print "in __call__ ..."
> > self.channel.send(val)
> >
> > class Switch(EventHandler):
> > def __init__(self,initialState=0,*outputs):
> > EventHandler.__init__(self,*outputs)
> > self.state = initialState
> >
> > def processMessage(self,val):
> > print "in processMessage() of Switch..."
> > self.state = val
> >
> > def notify(self,output):
> > print "in notify() of switch..."
> > output((self,self.state))
> >
> > class Reporter(EventHandler):
> > def __init__(self,msg="%(sender)s send message %(value)s"):
> > EventHandler.__init__(self)
> > self.msg = msg
> >
> > def processMessage(self,msg):
> > print "in processMessage() of Reporter..."
> > sender,value=msg
> > print self.msg % {'sender':sender,'value':value}
> >
> >
> > if __name__ == "__main__":
> > reporter = Reporter()
> > switch = Switch(0,reporter)
> > switch(1)
> >
> >
> >
> >
> > output:
> > =========
> >
> > in __call__ ...
> > in listen()...
> > in listen()...
> > in processMessage() of Switch...
> > in notify() of switch...
> > in __call__ ...
> > in processMessage() of Reporter...
> > <__main__.Switch instance at 0x8d822cc> send message 1
> >
> Is it because EventHandler has 2 subclasses, namely Switch and
> Reporter, and you have an instance of each?
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