From: Brian Candler <b.candler@...>
Date: 2009-02-02T06:10:00+09:00
Subject: Re: Could someone please explain the magic in this code

John Small wrote:
> (1) what does "<<-" do just before 'END_PRODUCT'
> (2) how do the lines after .result b get substituted into END_PRODUCT

Search for "here document" in 
http://www.ruby-doc.org/docs/ProgrammingRuby/html/language.html

It's essentially an inline string literal, from the line following 
<<-FOO until the line which has FOO.

> (3) How does binding work? The documentation is pretty opaque. What is
> it doing in this context and why is it required?

A binding is the environment in which variables are evaluated. If you 
pass a binding, it allows the local variables in your environment to be 
accessed from elsewhere.

irb(main):001:0> def foo(b)
irb(main):002:1> puts "x is #{eval("x",b)}"
irb(main):003:1> end
=> nil
irb(main):004:0> x = 4
=> 4
irb(main):005:0> foo(binding)
x is 4
=> nil

Note that normally the local variable x would not be accessible inside 
foo, which has its own scope.
-- 
Posted via http://www.ruby-forum.com/.