From: Robert Klemme <shortcutter@...>
Date: 2012-05-11T19:55:08+09:00
Subject: Re: passing via instance variable or regular ()

On Fri, May 11, 2012 at 12:32 PM, sam jam <lists@ruby-forum.com> wrote:
> "for a
> method there exists an additional precondition (i.e. that some
> instance variables are set in a particular way)."
>
> there is still a precondition in either case
>
> precondition: an instance variable is set in a particular way
>
>
>  def first
>    @name = "sam"
>    last
>  end
>
>   def last
>     name = @name + " " + "jam"
>   end
>
>
> precondition: something is passed to it (something set in a particular
> way)
>
>
> def first
>    name = "sam"
>    last(name)
>  end
>
>   def last(first)
>     name = first + " " + "jam"
>   end
>
>
> A lot of what you said I see as great points, but not that one because
> it is the same in either case.

But the precondition of having a method argument is automatically
enforced (if you do not use varargs) and you will immediately notice
something is missing.  In a way it is more obvious.  And then there
are still the other advantages
 - thread safety
 - no permanent side effects
 - no need to invoke additional methods before this method to set
instance state properly
etc.

Cheers

robert

-- 
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/