Re: String not enumerable, what about IO?

On Friday 20 October 2006 07:13, [e-mail] wrote:
> I do think that there's room to adjust and fine-tune how Enumerable
> works, but I wouldn't want to go in the direction of subordinating it
> to Array.

Another way of saying what Dave's saying is that Modules like Enumerable 
are "mix-ins".  They allow you to mix-in behavior based on the assumed 
presence of some core existing function.  Mix-ins are a very old concept 
originating (I believe) with Smalltalk.  The power lies in the fact that if 
you want to implement the functions in Enumerable, all you have to implement 
is a single function: each().

Mixins are similar to abstract classes in Java, only Rubyists tend to use them 
properly whereas (in my experience) most Java programmers don't understand 
the concept properly and so don't take full advantage of it.  Plus, you can 
mix in multiple modules in Ruby, whereas you can only inherit from a single 
abstract class in Java.  However, you *can* implement Enumerable in Java with 
abstract classes:

	pulic abstract class Enumerable {
		public boolean include( Object value ) {
			for (Iterator itter = getIterator(); itter.hasNext(); ) {
				Object curr = itter.next();
				if (curr.equals(value)) return true;
			}
			return false
		}
		// Etc.  Find, grep, collect, max... can all be defined using only
		// the information that we get in an iterator of the objects.
		public abstract Iterator getIterator(); 
	}

Enumerable is not synonymous with Array, and Strings only look like Arrays of 
characters because Americans first implemented them that way and everybody 
since has followed the convention.  ASCII still has a stranglehold on the 
computer industry. When you start venturing into I18N and start dealing with 
alternative encodings, then the analogy breaks down.  Which end of a String 
of Arabic (written right-to-left) characters do you start iterating from?  
What's the result of adding two of those strings together?

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