From: "Jesús Gabriel y Galán" <jgabrielygalan@...>
Date: 2012-11-27T02:36:49+09:00
Subject: Re: Novice: Understanding instance 'variables' and methods

On Mon, Nov 26, 2012 at 5:49 PM, Steve Tucknott <lists@ruby-forum.com> wrote:
> A question - or comment - on instance variables.
>
> Looking at ':symbols' today, I came across this example:
>
> class Test
>   puts :Test.object_id.to_s
>   def test
>     puts :test.object_id.to_s
>     @test = 10
>     puts :test.object_id.to_s
>   end
> end
> t = Test.new
> t.test
>
> So far, my understanding was that both methods and variables used lower
> case names, and that methods could be written both with and without
> '()'. To me that then made the t.test line a bit confusing, as it
> appears to invoke the method test on t. How then could you ever access
> the instance variable test of t?
>
> Am I then also right in assuming that in Ruby there aren't any true
> visible instance variables, as to make the variable visible, you have to
> include an accessor - which effectively creates the getter/setter of
> that variable?
>
> So if I changed the above code to have an instance variable of 'value',
> with an accessor, I could then have:
>
>
> @test = @value = 10
>
> and then access t.value - giving me 10. BUT t.value is then really a
> call to the 'generated' getter of value - so is really a method call?
>
> Do I have that about right?
>
> And in the above case, where a 'variable' and method have the same name,
> is there a way to force the use of a specific 'setter/getter' - ie to
> have t.test return the value of test, rather than call the method test
> on t?

As has been answered, you cannot get at the instance variables
directly from the outside. It's all calling methods.
But I think you have also another confusion, regarding *local*
variables and methods:

class A
  def test
     "test: the method"
  end
  def some_method
    test = "a variable"
    puts test #=> a variable
    puts self.test #=> test: the method
    puts test()  #=> test: the method
  end
end

If you have a local variable and a method with the same name, the
local variable "wins", and you have to use "self." or parenthesis to
tell Ruby you want to call the method.

Jesus.