From: Justin White <just6979@...>
Date: 2003-01-06T16:11:46+09:00
Subject: Re: should super's position be kept irrelevant?


On Sunday, January 5, 2003, at 06:07 , Tom Sawyer wrote:

> this is really just a question of taste i think, but i'm wondering if 
> you
> think super's position should be kept irrelevant? in the example below 
> the
> puts @avar will return nil. super has to be placed below @avar = 1 for 
> it to
> return 1.
>
> 	class Sup
> 		def initialize
> 			puts @avar
> 		end
> 	end
>
> 	class Chi < Sup
> 		def initialize
> 			super     # will puts nil
> 			@avar = 1
> 			# super  # would puts 1
> 		end
> 	end
>
> the other option to make it irrelevent is:
>
> 	class Sup
> 		def initialize
> 		end
> 		def go
> 			puts @avar
> 		end
> 	end
>
> 	class Chi < Sup
> 		def initialize
> 			super
> 			@avar = 1
> 			go
> 		end
> 	end
>
> of course, now go's position is important, but not super's. which is
> preferrable?
>

to me, that's the least suprising way to work. when you call super 
before setting the instance variable, the puts of the variable springs 
it into existence with nil as a value (Perl calls it autovivification i 
think). the output comes before the setting of the variable, and nothing 
happens after setting it.

in the second setup, super.initialize doesn't DO anything, but #go does, 
and the instance variable is set BEFORE #go is run. super's position in 
the second example isn't important because super.initialize is not doing 
anything ;)

-Justin