Comments on: Why No Love for the Monostate Pattern in ActionScript 3?

By: james

james — Mon, 15 Dec 2008 10:38:30 +0000

Hi Matt,

not sure if you’ve seen this, but it’s definately worth a read…

https://segueuserfiles.middlebury.edu/xp/SingletonAndMonostate.pdf

By: james

james — Tue, 09 Dec 2008 17:51:15 +0000

I’d have to agree with Todd. A Factory only limits the amount of instances that can be created, not the way in which they are implemented, as is the case with both the Singleton and MonoState. This makes it instantly more flexible.

By: todd anderson

todd anderson — Mon, 24 Nov 2008 00:05:55 +0000

Nice discussion. I guess for me, i would stay away from the monostate as a ‘model locator’. It may just be personal taste, but anything static connotes to me as being a utility.

If you want a true single instance of an implementation without having to resort to Singletons or a model being self-aware of its use, i would go for an instance of a Factory that keeps a single representation of an implementation rather than go with a Singleton or monostate.

Of course this really all boils down to the size of the development team and individual comfort. I can definitely see where your example will be beneficial and could develop against it if the case presents itself. But i personally would not use it – meaning that it goes against my notions of static properties, not that it is a bad implementation.

By: Matt

Matt — Thu, 20 Nov 2008 21:51:55 +0000

I never said Monostate is better than Singleton. I’m just curious about the pros and cons of using one or the other when attempting to ensure only you have only one instance of something. Monostate seems attractive in some ways, but I also have no problem using Singleton. This “debate” seems to be rather unique and spurs some very opinionated responses. Again, I don’t have a preference really. Just wanted to see what other people think because the Monostate pattern isn’t very prevalent in the ActionScript world.

By: Fedlarm

Fedlarm — Thu, 20 Nov 2008 10:20:40 +0000

“That is the whole point of the monostate pattern – the static property has one value that is shared by all instances of the class and derived classes.”

Yes I can I see that, but, he compares this pattern to Singleton, so I tried to argue for an issue with Monopattern compared to Singleton. Matt, says that it is far better than Singleton, I don’t agree on that. I think it is more simple to use, but it cannot always replace the Singleton, because of the difference on inheritance.

By: Bjorn Schultheiss

Bjorn Schultheiss — Thu, 20 Nov 2008 03:56:12 +0000

Yes.. It uses a factory to create the Presentation Models that get passed via reference to the views..
it injects the delegate in the command and injects the service in the delegate.