redefined> Here is another non-pythonic question from the Java
redefined> Developer. (I beg for forgiveness...)
redefined> Does Python have a mechanism for events/event-driven
redefined> programming?
The enthought traits package has built-in support for event handling,
among other things
http://code.enthought.com/traits/
Here is an example from the web page:
from enthought.traits import Delegate, HasTraits, Int, Str, Instance
from enthought.traits.ui import View, Item
class Parent(HasTraits):
first_name = Str('') # INITIALIZATION:
last_name = Str('') # 'first_name' and
# 'last_name' are
# initialized to ''
class Child(HasTraits):
age = Int
father = Instance(Parent) # VALIDATION: 'father' must
# be a Parent instance
first_name = Str('')
last_name = Delegate('father') # DELEGATION:
# 'last_name' is
# delegated to
# father's 'last_name'
def _age_changed(self, old, new): # NOTIFICATION:
# This method is
# called when 'age'
# changes
print 'Age changed from %s to %s ' % (old, new)
traits_view = View(Item(name='first_name'), # TRAITS UI: Define
Item(name='last_name', # the default window
style='readonly'), # layout
Item(name='age'),
Item(name='father'))
####################################################
# Make and manipulate objects from the classes above
####################################################
joe = Parent()
joe.last_name = 'Johnson'
# DELEGATION in action
moe = Child()
moe.father = joe
print "Moe's last name is %s" % (moe.last_name)
# NOTIFICATION in action
moe.age = 10
#VISUALIZATION: Display the UI
moe.configure_traits()
The DELEGATION and NOTIFICATION segments in the above example yield
the following command-line output:
Moe's last name is Johnson
Age changed from 0 to 10
