From: Tom Sawyer <transami@...>
Date: 2002-08-12T21:51:23+09:00
Subject: Re: ambiguity backtrack - accessors and persistent locals

On Fri, 2002-08-09 at 13:30, Dave Thomas wrote:
> This is an interesting issue: should internal users go via the setter
> method or access the instance variable directly. Clearly it depends on
> the circumstances, but I often find myself writing accessors that do
> things such as lazy evaluation, or which set dirty flags for
> persistent objects, and where I really do need to go via the method
> form. For those times, it's nice to have a shortcut, but it isn't
> something I'd fight hard for... :)

i'd like to refocus on this aspect of the ambiguity thread. from what's
been posted thus far on the topic, it would seem it is best to always
use the accessor methods when they exist. i hanker to bet many of us do
not do this. and i think this has to do with the fact that the
@variables are more convenient, due to the extra thoguht that must go
into determining when self must be used (albiet small), and the fact
that @ is shorter than self. other reasons?

so your idea for the . shortcut may be very helpful in encouraging
better programming along these lines. currently ruby allows for space to
exist between the reciever, the dot, and the message call, but i imagine
it would be short work to adjust, and very rare to cause any code
breakage.

yet, i start to wonder, if using getter and setter methods is really how
instance variables should be effected in OOP, and not forgetting kents
discussion of "minimizing" the use of @ and @@ via accessor methods,
persistent local variables make worthy of consideration. a persitent
local variable is simply a variable whose value is not lost from one
call to the method it resides in to the next. quick psuedo-example:

  def x(n)
    persist :x
    x = x + n
  end

  puts x(10)   # --> 10
  puts x(20)   # --> 30

-- 
~transami