From: Anders Borch <spam@...>
Date: 2003-07-01T06:04:27+09:00
Subject: Re: why can't I access my instance variables?

Donglai Gong wrote:

> I'm having trouble accessing instance variables directly.  What's wrong 
> with this...
> 
> class Level1
>   def initialize
>     @var1='var1 set.'
>   end
> 
>   def printvar1
>     @var1
>   end
> end
> 
> l1=Level1.new
> print l1.printvar1, "\n"
> print l1.var1
> 
> I get the following output:
> 
> % ruby test.rb
> var1 set.
> test.rb:13: undefined method `var1' for #<Level1:0x23d5e8 @var1="var1 
> set."> (NoMethodError)
> 
> I'm running version 1.8.0 preview3 on OS X.
> 
> Donglai
> 
> 


variables are private by default. You can write get and set methods to 
read and write their values.

class Level1
   def initialize
     @var1='var1 set.'
   end

   def printvar1
     @var1
   end

   def var1
     @var1 # just return @val1
   end

   def var1= (newval)
     # test the validity of newval here
     @val1 = newval
   end

end

if you feel lazy and have no need to have any tests in your accessor 
methods (get and set methods) then there is:

class Foo
   attr_reader :readable_var
   attr_writer  :writable_var
   attr_accessor :readable_and_writable_var
end

I hope this helps :)

-- 
dc -e 
4dd*od3*dddn1-89danrn10-dan3+ann6*dan*2*an13dn1+dn2-dn3+5*ddan2/9+an13nap