Python class structure ... prep() method?
- by Adam Nelson
We have a metaclass, a class, and a child class for an alert system:
class AlertMeta(type):
"""
Metaclass for all alerts
Reads attrs and organizes AlertMessageType data
"""
def __new__(cls, base, name, attrs):
new_class = super(AlertMeta, cls).__new__(cls, base, name, attrs)
# do stuff to new_class
return new_class
class BaseAlert(object):
"""
BaseAlert objects should be instantiated
in order to create new AlertItems.
Alert objects have classmethods for dequeue (to batch AlertItems)
and register (for associated a user to an AlertType and AlertMessageType)
If the __init__ function recieves 'dequeue=True' as a kwarg, then all other
arguments will be ignored and the Alert will check for messages to send
"""
__metaclass__ = AlertMeta
def __init__(self, **kwargs):
dequeue = kwargs.pop('dequeue',None)
if kwargs:
raise ValueError('Unexpected keyword arguments: %s' % kwargs)
if dequeue:
self.dequeue()
else:
# Do Normal init stuff
def dequeue(self):
"""
Pop batched AlertItems
"""
# Dequeue from a custom queue
class CustomAlert(BaseAlert):
def __init__(self,**kwargs):
# prepare custom init data
super(BaseAlert, self).__init__(**kwargs)
We would like to be able to make child classes of BaseAlert (CustomAlert) that allow us to run dequeue and to be able to run their own __init__ code. We think there are three ways to do this:
Add a prep() method that returns True in the BaseAlert and is called by __init__. Child classes could define their own prep() methods.
Make dequeue() a class method - however, alot of what dequeue() does requires non-class methods - so we'd have to make those class methods as well.
Create a new class for dealing with the queue. Would this class extend BaseAlert?
Is there a standard way of handling this type of situation?
