C#•3mo ago

✅ Confused when try to implement Factory Method

I'm learning design patterns starting from the factory method. what I'm confused about is the first initialization to be used as a reference to be manipulated, for example as follows: https://hastebin.com/share/kohugizayu.csharp These 3 variables are needed for the movement (and maybe initialization) of the player later and it looks like it should be done in each concrete product, so where should I declare these 3 variables in the factory method implementation? if I declare it in each concrete product it will look like duplication code. Any suggestions? Thanks

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9 Replies

SleepWellPupper•3mo ago

You could abstract position, size and speed out of your concrete classes into an abstract base class:

abstract class CoreBase(Vector2 position, Vector2 size, float speed) : ICore
{
    protected Vector2 Position { get; set; } = position;
    protected Vector2 Size { get; } = size;
    protected float Speed { get; } = speed;
    public abstract void movement();
}

abstract class CoreBase(Vector2 position, Vector2 size, float speed) : ICore
{
    protected Vector2 Position { get; set; } = position;
    protected Vector2 Size { get; } = size;
    protected float Speed { get; } = speed;
    public abstract void movement();
}

Have your concrete cores implement that by inheriting from CoreBase. Also, you should rename movement to Move because - methods should be verbs as they do things - methods should be pascal case as that is the convention in C# it's less of a problem concerning the factory and more of a concern of your type hierarchy You are implementing the Abstract Factory pattern, whose purpose is two-fold: - hide the implementation type - hide the initialization complexity Your current initialization effort is nil, but that might change in the future if you want to, say, let users provide the position, size and/or speed of a produced ICore. In that case, you could add constructors to your concrete cores and modify the factory interface (ShapesCreator) to take those constructor parameters.

Nectar•3mo ago

thanks for the advice!

SleepWellPupper•3mo ago

$close

MODiX•3mo ago

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Nectar•3mo ago

Sorry, I have another question. My first question: after the changes you suggested, can my code still be called a factory method? because it changes the structure of the UML diagram. Second: what does initialization mean when you say my code implements abstract factory? After you mentioned abstract factory I tried to understand and compare the two, but it raised a third question. Third: can you give an example and explain when to use one over the other in an easy to understand sentence? Thank you very much and sorry for responding so late, I thought no one would respond.

SleepWellPupper•3mo ago

1. You can call anything that is concerned with creating an instance of another type a factory; methods or types are generally called factories. A "dumb" factory that just does Create() => new Foo() is still a factory. 2. Initialization is any operation you do as a prerequisite to or in service of the process of creating an instance. Fetching constructor arguments, calculating expensive values etc. account for the initialization effort. In your case, getting the initial Position, Size and Speed values for created cores would be initialization effort in the factory. You could have users provide these values via the factory methods parameters. Initialization and Abstract Factory related only in that a factory performs initialization, and Abstract Factory is a factory. 3. On reading further into the subject, it seems you are indeed implementing a regular factory. The difference being that a regular factory produces one kind of object, whereas an abstract factory produces a family. You can read more about factories here, here and here.

Abstract Factory

Abstract Factory is a creational design pattern that lets you produce families of related objects without specifying their concrete classes.

Baeldung on Computer Science

Factory Method vs. Factory vs. Abstract Factory | Baeldung on Compu...

Learn about the Factory pattern and all its flavors.

Nectar•3mo ago

I'll take that as a reference, thank you very much! can i send you a friend request?

SleepWellPupper•3mo ago

sure

Nectar•3mo ago

I can't send it, I think because the request is disabled. well, i will read those first. again, thank you!

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✅ Confused when try to implement Factory Method