Re: Difference between Factory and Abstract Factory

Responding to EvilOldGit...

I've read the gang of four, and various things I've googled, but I'm
just too stupid to really get the difference between a factory and an
abstract factory.

The difference lies in how dynamic the substitution needs to be. In both cases the Product and the Factories to produce them are generalizations. The difference is that in Factory Method the subclasses in each generalization map 1:1 to each other while in Abstract Factory the Factory subclasses map 1:* to Product subclasses.

Thus in Factory Method a concrete factory object can instantiate exactly one flavor of one Product. But in Abstract Factory a single concrete factory object can instantiate a different flavor of Product from each of multiple Product generalizations. IOW, one uses Factory Method when there is only one family of products and one uses Abstract Factory when there are construction similarities across multiple families of products.


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