From: Stefano Crocco <stefano.crocco@...>
Date: 2007-10-05T03:32:40+09:00
Subject: Re: (Newbie) Override * on Array

Alle giovedì 4 ottobre 2007, Mike Ho ha scritto:
> Stefano Crocco wrote:
> > require 'generator'
> >
> > class Array
> >
> >   def *(other)
> >     SyncEnumerator.new(self, other).map{|x, y| x*y}
> >   end
> >
> > end
> >
> > Regarding errors, you I think you can check the size of the two array at
> > the
> > beginning of the method and raise TypeError if they're different.
> >
> > I hope this helps
> >
> > Stefano
>
> Thanks for the replies guys.
>
> The SyncEnumerator looks elegant but when I tried it I got the following
> error
>
> in `*': undefined method `*' for nil:NilClass (NoMethodError)
>
> for the line
>
>  SyncEnumerator.new(self, other).map{|x, y| x*y}
>
>
> I call the method by...
>
> a1=[2, 4, 6]
> a2= [2, 2, 2]
>
> puts a1*a2
>
> I put some debug in like this
>
>  def *(other)
>       SyncEnumerator.new(self, other).map  do |x,y|
>       puts "x #{x}  y #{y}"
>       x*y
>     end
>   end
>
> and the output I get is this
> x 2  y 2
> x 4  y 2
> x 6  y 2
> x   y
> C:/ruby_work/test/scratch.rb:23:in `*': undefined method `*' for
> nil:NilClass (NoMethodError)
> So it seems to 'run off the end'
>
> Any thoughts ?
>
> Thanks


This is strange. It works correctly for me:

require 'generator'

class Array

  def *(other)
    SyncEnumerator.new(self, other).map{|x, y| x*y}
  end

end

a1 = [2,4,6]
a2 = [2,2,2]
puts a1*a2
=> 4
   8
   12

I can't understand why it isn't working for you.

Stefano