Differences between Abstract Factory Pattern and F

Question

I know there are many posts out there about the differences between these two patterns, but there are a few things that I cannot find.

From what I have been reading, I see that the factory method pattern allows you to define how to create a single concrete product but hiding the implementation from the client as they will see a generic product. My first question is about the abstract factory. Is its role to allow you to create families of concrete objects in (that can depend on what specific factory you use) rather than just a single concrete object? Does the abstract factory only return one very large object or many objects depending on what methods you call?

My final two questions are about a single quote that I cannot fully understand that I have seen in numerous places:

One difference between the two is that with the Abstract Factory pattern, a class delegates the responsibility of object instantiation to another object via composition whereas the Factory Method pattern uses inheritance and relies on a subclass to handle the desired object instantiation.

My understanding is that the factory method pattern has a Creator interface that will make the ConcreteCreator be in charge of knowing which ConcreteProduct to instantiate. Is this what it means by using inheritance to handle object instantiation?

Now with regards to that quote, how exactly does the Abstract Factory pattern delegate the responsibility of object instantiation to another object via composition? What does this mean? It looks like the Abstract Factory pattern also uses inheritance to do the construction process as well in my eyes, but then again I am still learning about these patterns.

Any help especially with the last question, would be greatly appreciated.

Answer 1

1. My first question is about the abstract factory. Is its role to allow you to create families of concrete objects in (that can depend on what specific factory you use) rather than just a single concrete object?

Yes. The intent of Abstract Factory is:

Provide an interface for creating families of related or dependent objects without specifying their concrete classes.

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2. Does the abstract factory only return one very large object or many objects depending on what methods you call?

Ideally it should return one object per the method client is invoking.

3. My understanding is that the factory method pattern has a Creator interface that will make the ConcreteCreator be in charge of knowing which ConcreteProduct to instantiate. Is this what it means by using inheritance to handle object instantiation?

Yes. Factory method uses inheritance.

4. Abstract Factory pattern delegate the responsibility of object instantiation to another object via composition? What does this mean?

AbstractFactory defines a FactoryMethod and ConcreteFactory is responsible for building a ConcreteProduct. Just follow through the code example in this article.

You can find more details in related SE posts:

What is the basic difference between the Factory and Abstract Factory Patterns?

Design Patterns: Factory vs Factory method vs Abstract Factory

Answer 2

Abstract Factory is an interface for creating related products, but Factory Method is only one method. Abstract Factory can be implemented by multiple Factory Methods.