Events¶
Events will notify the implementation that things happened. They are called asynchronously, the result will be ignored.
There are three ways to define events, by creating them in the inherited handler, by setting target objects in the handlers events property and by registering events.
Inherited handler¶
When working with a inherited class, events can be implemented by creating members with a specific name:
class SampleEquipment(secsgem.GemEquipmentHandler):
def __init__(self, address, port, active, session_id, name, custom_connection_handler=None):
secsgem.GemEquipmentHandler.__init__(self, address, port, active, session_id, name, custom_connection_handler)
def _on_event_hsms_selected(self, connection):
pass
In this example when the hsms connection state changes to selected the _on_event_hsms_selected method will be called.
A generic representation of the function would be:
def _on_event_<event_name>(self, <parameters>):
pass
To catch all events, the _on_event method can be overridden:
class SampleEquipment(secsgem.GemEquipmentHandler):
def __init__(self, address, port, active, session_id, name, custom_connection_handler=None):
secsgem.GemEquipmentHandler.__init__(self, address, port, active, session_id, name, custom_connection_handler)
def _on_event(self, *args):
pass
Target objects¶
These methods don’t need to be implemented on the handler itself.
Other objects can also be registered using the event member names of the handler.
The _on_event_<event_name> and _on_event methods are then searched in that object:
class TestClass:
def _on_event_hsms_selected(self, connection):
pass
t = TestClass()
handler.events.targets += t
The event handler can work with more than one target objects.
Registering events¶
Events can also be registered from outside a class:
def f_hsms_selected(connection):
pass
handler.events.hsms_selected += f_hsms_selected
To unregister simply remove the member:
handler.events.hsms_selected -= f_hsms_selected