Implement Mixin In Java? [closed]

Answer 1

I am exploring providing this for Java 7. My first cut will be to use the example shown in this article:

• Mixins in Pure java

It ought to work with java 6, it is similar to the other injection options above. Based on my experience with Mixins in C# and Ruby, you should aim to implement mixins, not just emulate or fake it.

Another model, is the one used with Jackson:

• Jackson MixIn Annotations

If you can use the new Java 8 release, say if you are in pre-release mode, that might help.

• Java 8: You now have mixins?

Using Virtual Extension method, which requires effort to 'be-a' mixin. So in my mind it is still early days and I prefer the cleaner looking approach (or similar) offered by the first link.

Answer 2

Please have a look of my small demonstration project how to create mixins in pure java using cglib. Mainly it is just a call to a proxy generator. This is ally. The example contains an junit test case demonstrating how to instantinate the proxy.

https://github.com/literadix/JavaMixins

Answer 3

Yes, the most simple and convinient way to implement mixins apporoach in Java - is to use static import from some class which contains static methods.

Answer 4

I'd say just use object composition. Every time you want to throw in new functionality, compose another object into the class as a member. If you want to make all of your mixed-in classes of the same type, you can use an array as a member object where each element is composed with all of the others, and you can dispatch to a particular element.

Answer 5

In the sense that a Ruby mix-in is the equivalent of a Java abstract class, no, you cannot implement a mix-in in Java. You can come close by using interfaces and thus defining absolutely no code in your mix-in, but you cannot directly achieve the same behavior as in a Ruby mix-in.

Answer 6

Since Java only supports single inheritance, that is not possible. Have a look at WP: Mixin.

EDIT: Because of the comments about interfaces: The cool thing about mixins is that you can combine them without writing the combination's code. With interfaces you have to implement the combination's functionality yourself (except one class you can extend)!