From: Matthew Smillie <M.B.Smillie@...>
Date: 2005-12-09T00:31:53+09:00
Subject: Re: Best Practice Advise for a Total Ruby Beginner

On Dec 8, 2005, at 15:17, cros wrote:
>
> I found I had to make a method to access the "created" instance var in
> the Message class in the sort block.  I tried using a.@created and
> b.@created but it threw a syntax error.  So, my question: Is making a
> method simply to access a var as in this case "good programming"?
>
> Paul


Basically, yes.  It's generally referred to as 'encapsulation' in  
object-oriented circles.  One big advantage that's often cited is  
that if you change the internal representation of 'created' in  
Message (say, to seconds since 1970 or something), you only change  
the accessor method to maintain compatibility.  If you directly  
accessed the variable, you'd have to change every piece of code that  
used Message to keep it compatible.

As I'm sure will be pointed out before I manage to send this off,  
Ruby provides some shortcuts for making these methods:

class Message
   attr :created
   def initialize(created)
     @created = created
   end
end

'attr' is a method which adds accessor methods to the class for its  
arguments.  The arguments are symbols which correspond to variable  
names you want the accessors for.

matt.