Andre Meyer wrote:
> While looking for an elegant implementation of the singleton design
> pattern I came across the decorator as described in PEP318
> <http://www.python.org/dev/peps/pep-0318/>.
> Unfortunately, the following does not work, because decorators only work
> on functions or methods, but not on classes.
>
> def singleton(cls):
> instances = {}
> def getinstance():
> if cls not in instances:
> instances[cls] = cls()
>
> return instances[cls]
> return getinstance
>
> @singleton
> class MyClass:
> ...
>
>
> Am I missing something here? What is the preferred pythonic way of
> implementing singleton elegantly?
You can always use the syntax the decorator replaces:
class MyClass:
...
MyClass = singleton(MyClass)
But there are better ways, and maybe you don't even need a singleton.
See the Python Cookbook.
Georg
--
http://mail.python.org/mailman/listinfo/python-list
