From: Jim Weirich <jim@...>
Date: 2006-02-25T06:58:41+09:00
Subject: Re: Private methods - only available to oneself?

James Byrne wrote:
> I do not understand why within the class definiton the Ruby interpreter 
> distinguishes between implicit and explict calls to self.

Possibly because it allows you[1] to examine the code and statically 
determine if a private method is allowed.  If the implicit receiver rule 
were not used, then is the following a valid use of a private method?

   def f(other)
     other.private_method
   end

Well, maybe or maybe not.  It depends how it is called.

   f(self)    # private method inside of f is ok
   f(you)     # private method inside of f is probably not ok,
              # (but it really depends on the value of you, doesn't it)

By using the implicit receiver rule, we know for sure that calling 
"private_method" in f is not ok.  Less ambiguity.

BTW, the Eiffel language also uses instance based protection (like Ruby) 
and also uses the implicit receiver rule as well.  So there is 
precedent.

--
-- Jim Weirich

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