From: Christian Boos <cboos@...>
Date: 2002-02-22T22:18:07+09:00
Subject: RE: recursive require

Hello,

> -----Original Message-----
> From: ysantoso@thomases.com [mailto:ysantoso@thomases.com]On Behalf Of
> Yohanes Santoso
> Sent: Friday, February 22, 2002 12:00 PM
> To: ruby-talk ML; undisclosed-recipients:
> Subject: Re: recursive require
...
> Here are three files, abc.rb, xyz.rb, and global.rb. abc contains
> class Abc, and xyz contains class Xyz. Abc and Xyz are
> inter-dependant.  Putting "require 'xyz'" in abc.rb and "require
> 'abc'" in xyz.rb will not work as you pointed out.
> 
> So, pre-declare class Abc in xyz.rb and pre-declare class Xyz in
> abc.rb. However, rather than putting the declaration everywhere,
> collect them into a file: global.rb.
> 
> Then, from abc.rb and xyz.rb require global.rb
> 
...

While forward decl. could work that way in Ruby,
I think it is a pattern coming from C/C++ that
doesn't need to be transposed in Ruby.

In this case, I would suggest requiring the other
file just before you need it:

=== abc.rb ===
class Abc
  def Abc.name
    "abc"
  end

  def whoami
    puts "abc knows xyz:"

    require 'xyz'
    puts Xyz.name

    puts "abc tells the truth"
  end
end
a = Abc.new
a.whoami


=== xyz.rb ===
class Xyz
  def Xyz.name 
    "xyz"
  end
  def whoami
    puts "xyz knows abc:"

    require 'abc'
    puts Abc.name

    puts "xyz tells the truth"
  end
end
x = Xyz.new
x.whoami


=== *ruby* ===
irb(main):001:0> require 'abc'
abc knows xyz:
xyz knows abc:
abc
xyz tells the truth
xyz
abc tells the truth
true



-- Christian