Robert Klemme wrote:
> On 18.02.2009 15:18, Aldric Giacomoni wrote:
>> Robert Klemme wrote:
>>> 2009/2/18 Aldric Giacomoni <"aldric[removeme]"@trevoke.net>:
>>>  
>>>> I know I could just use rubytree, which looks quite nice, but I'd like
>>>> to see what you guys would do about creating a tree and linking the
>>>> nodes together.
>>>> In C++ we'd just make pointers, so how would we do the equivalent 
>>>> in Ruby?
>>>>     
>>> We use object references - as always when referring other objects.
>>> Ruby does not have the multitude of options that C++ has.
>
>> Alright, Robert - I don't know how that works in Ruby! Would you provide
>> me with a simple example, explain it, or point me to something that
>> explains it, please?
>
> I wasn't aware that you were after _such_ basic information.  
> Actually, since you mentioned using rubytree I assumed that you are 
> familiar with the language.  The simplest and most basic form of a 
> relation between two objects is probably:
>
> class Foo
>   def set(x)
>     @the_other = x
>   end
> end
>
> f = Foo.new
> x = Foo.new
> f.set(x)
>
> Now f references x.
>
> I suggest you get your hands on David's new book once it is out and in 
> the meantime consult those various introductory documents (can be 
> found via http://www.ruby-doc.org/).
>
> Cheers
>
>     robert
>
Essentially, the main information you require is that, everything in 
Ruby is an object, and every object is actually a reference to an object.

so
class Foo

  attr_reader :the_other

  def set(x)
    @the_other = x
  end
end

f = Foo.new
bar = f
bar.the_other => nil
x = Foo.new
f.set(x)
bar.the_other => x

It helps me to think of references and the objects they point to as 
separate entities (I'm unsure of the truthfulness of this).  It's the 
opposite of c++ really.  c++ requires you to explicitly state you want 
pass-by-reference and Ruby requires you to state pass-by-value (which 
ends up in the form of a .dup call all the times I've ever wanted to use 
it, which is less often than you might think)

Cheers,
Michael

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