Given a class that keeps a registry of its Objects:
class Person(object):
__registry = []
def __init__(self, name):
self.__registry.append(self)
self.name = name
How would I make the following code work (without using Person.__registry):
for personobject in Person:
print personobject
While researching I found a hint that one could go for a __metaclass__ with a __getitem__-method. Any ideas how this would look like?
You can make your class object iterable with a simple metaclass.
class IterRegistry(type):
def __iter__(cls):
return iter(cls._registry)
class Person(object):
__metaclass__ = IterRegistry
_registry = []
def __init__(self, name):
self._registry.append(self)
self.name = name
(I have also changed __registry to _registry to make it easier to access from the metaclass).
Then,
>>> p = Person('John')
>>> p2 = Person('Mary')
>>> for personobject in Person:
... print personobject
...
<person.Person object at 0x70410>
<person.Person object at 0x70250>
First, do not use double __ names. They're reserved for use by Python. If you want "private" use single _.
Second, keep this kind of thing as simple as possible. Don't waste a lot of time and energy on something complex. This is a simple problem, keep the code as simple as possible to get the job done.
class Person(object):
_registry = []
def __init__(self, name):
self._registry.append(self)
self.name = name
for p in Person._registry:
print p
you can do it with:
for item in Person.__registry:
print(item)
