Guy Wiener

My Advisor, Dr. Mayer Goldberg, claims that object-oriented programming is like functional programming, only with named arguments. Objects are closures. Constructors are lambdas. Invoking a method is applying the closure. That’s it.

I faced a good demonstrations of that claim while I was working on a small code generator. I wanted to exploit Java’s annotation processing, so I can make this generator a part of a build process. The annotation processing mechanism uses the visitor design pattern extensively. By “extensively” I actually mean “you cannot get a concrete value without using at least two visitors”. These visitors are:

1. Element visitor: Since Java code is composed of packages, classes, methods and so on, you need a visitor to tell you which kind of element you are currenly holding.
2. Type visitors: A type in Java can be a declared type (class, interface, etc.), an array type, primitive type and so forth, so you need a visitor to tell you which type is which.

The task that I had at hand looked simple: Given a class with methods that has a parameteric return type, get the type argument that is not the class. For example, for this class and method:

public class A {
  Association<A,B> getAB();
}

Return the element representing the type “B”. Simple enough, no?
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