subclass

A Java Factory Pattern (Factory method) example

Java Design Patterns FAQ: Can you provide an example of the Factory Pattern in Java?

Sure. In this article we'll look at a small-but-complete example of the Factory Pattern ("Factory Design Pattern") implemented in Java.

How to define a Scala trait so it can only be subclassed by a certain type

This is an excerpt from the Scala Cookbook (partially modified for the internet). This is Recipe 8.6, “How to mark a Scala trait so it can only be subclassed by a certain type.”

Problem

You want to mark your trait so it can only be used by types that extend a given base type.

Solution

To make sure a trait named MyTrait can only be mixed into a class that is a subclass of a type named BaseType, begin your trait with a this: BaseType => declaration, as shown here: