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From: Hyman Rosen <hymie@prolifics.com>
Subject: Re: Dummy
Date: 2000/02/07
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Florian Weimer <someone@deneb.cygnus.argh.org> writes:
> This prints `3' and `4', doesn't it?  Cool.  I didn't know that Java
> supports class closures.  Now Java only needs operator overloading
> and some syntactic sugar for dispatching by name and introspection,
> and Java will become my favorite scripting language. ;)

Actually, I'm wrong about this. I was over-ambitious. The following
similar code does work, though. The trick is that the "closures" are
fake - behind the scenes, Java copies the referenced locals into the
local class, and only lets you do this with "final" variables.

class a
{
	interface i
	{
		int get();
		void set(int n);
	}
	class my_int implements i
	{
		int val;
		public int get() { return val; }
		public void set(int n) { val = n; }
	}
	i local_ref()
	{
		final my_int local = new my_int();
		return new i () {
			public int get() { return local.get(); }
			public void set(int n) { local.set(n); }
		};
	}
	public static void main(String[] v)
	{
		a my_a = new a();
		i i1 = my_a.local_ref();
		i i2 = my_a.local_ref();
		i1.set(3);
		i2.set(4);
		System.out.println(i1.get());
		System.out.println(i2.get());
	}
}