From: Stephan Dale <ruby-forum@...>
Date: 2007-07-31T20:54:19+09:00
Subject: Re: rdoc and virtual attributes

I'm just worried that by using the attr_ methods where you'd not 
normally do so, simply for documentaion purposes, increases the risk 
that you forget their programmatic effects.

e.g. I've defined a virtual attribute called foo and I've used 
attr_writer to document it as a normal attribute. Problem is that I've 
forgotten to override the setter. By inspection we can see that the use 
of foo= sets @foo, but foo doesn't get @foo, hence showing that foo is a 
virtual attribute and exposing some of the underlying implementation.

class Bar

  # foo isn't a virtual attribute, honest!
  attr_writer :foo

  # oh yes it is.
  def foo # :nodoc:
    @foo+1
  end

end

irb(main):011:0> b = Bar.new
=> #<Bar:0xb78fd04c>
irb(main):012:0> b.foo = 1
=> 1
irb(main):013:0> b
=> #<Bar:0xb78fd04c @foo=1>
irb(main):014:0> b.foo
=> 2

I was hoping that there was a way of flagging a method as representing a 
virtual attribute rather than having to rely on the attr_ methods.

e.g. def foo # :virtual:
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