Question

I have a Phidgets stepper controller (Stepper class) and it allows event handlers to be methods of the class:

self.setOnAttachHandler(self.StepperAttached)
self.setOnDetachHandler(self.StepperDetached)

These are useful as they can perform tasks when the stepper controller is attached/detached from the PC.

I have created a Stepper object in a wxFrame in Python and would like to know how to send those messages to the wxFrame so that it can, for example, indicated that the controller has been attached/dettached without polling.

Or in general, how do I send events/messages from object to parent in Python?

Thanks!

Answer 1

The canonical way to do this is to pass a reference of the parent object down into the children.

from Phidgets.Devices.Stepper import Stepper

class Parent(object):
    "Parent Class"

    def stepperAttached(self, event):
        print 'Connected to device ', event.device.getSerialNum()

    def eventHandler (self, event):
        print "Event fired!", event.state

class Child(object):
    "Child class"

    def __init__(self, parent):
        self.parent = parent
        self.stepper =  Stepper()
        self.stepper.setOnAttachHandler(self.parent.StepperAttached)
        self.stepper.setOnInputChangedHandler(self.parent.eventHandler)

p = Parent()
c = Child(p)
c2 = Child(p)
# etc..

Hopefully this helps. Code might not be quite accurate, as I don’t have a reference handy, but the principal is the same even if the code above is slightly off.