From: Eric Schwartz <emschwar@...>
Date: 2006-03-16T07:28:47+09:00
Subject: Re: Ruby for Java Folks?

"Wilson Bilkovich" <wilsonb@gmail.com> writes:
> How about working through some of the examples from Refactoring by
> Martin Fowler, or Smalltalk Best Practice Patterns by Kent Beck, using
> both Java and Ruby side-by-side?

Most of my good books (like Refactoring) are packed up, alas!  But
I'll see if I can't come up with some simple examples of "Here's how
you do it in Java, now here's Ruby".  I want to avoid appearing to
diss Java at all; these are presumably smart people who don't care to
have advocacy thrown at them; I just want to give them info.

> One thing I really like about Ruby is that certain tasks (like
> enumeration) have much less code overhead than in Java, which promotes
> nice, small methods that are easy to refactor or rework.  Even if it's
> only 6 lines, there's some mental resistance to setting up a loop in
> Java.

Yeah, I have to admit that, having done some C recently (had to
interface with a new device driver, and didn't want to learn how to do
ioctls in Ruby at the time), I hate doing C/Java-style for loops like
this:

String [] fileNames = new File( "/home/emschwar" ).list();
for(int i=0; i < fileNames.length; i++) {
   System.out.println("directory entry named [" + fileNames[i] + "]");
}

There's no real reason for it, but it focuses my mind more on the
array (how I set it up, how I'm iterating over it) when I'm reading it
than in the Ruby below:

Dir.entries('/home/emschwar').each { |e|
   puts "directory entry named [#{e}]"
}

Here, I'm more focused on what I'm doing to each element-- this
reminds me a lot more of Perl's map (and Lisp's mapcar) function, but
when I use Perl, I feel like I'm turning the iteration inside out;
here it's just a much simpler way of doing the same for loop above.
Without complaining about Java, showing how Ruby iteration eliminates
the need for explicit iterators would certainly be powerful stuff.

(personally, I prefer do...end, but used {} here to make Java people
feel more comfortable :)

-=Eric