Tuesday 12 April 2005 12:09 pm Michele Simionato wrote: > Steven Bethard: >> It strikes me that I've never wanted or needed a singleton object. >> Would you mind sharing your use case? I'm just curious. > > "Singleton" is the most idiotic pattern ever. If you want an instance, > just > instantiate your class once. If a class should have only one instance, > you can just document it. What I find usuful is "memoize", which > contains "Singleton" as a special case. So I use memoize even > for singleton would-be, i.e. logfiles and databases connections > (memoizing the connections, if I try to open a database twice with the > same parameters, I am returned an instance of the already opened > database).
"Singleton" is simple (like the wheel), but that does not make it stupid. There are two aspects that are important: 1. a Singleton has one, very simple property and virtually everyone knows what you talk about when you explain that you used a "Singleton". In this case its just a technical term. We need technical terms. 2. the property of a Singleton, i.e. there is only one, is important - you use it yourself through memoize. That is just a more flexible implementation of having one instance of whatever you memoize. Using @memoize on the __new__ method works very well and is flexible enough to be used with any function call. Thanks for the tip. Ciao Uwe -- http://mail.python.org/mailman/listinfo/python-list
