[ruby-talk:02381] Re: Iterator into array

[e-mail] (YANAGAWA Kazuhisa) writes:

> In message <[e-mail]>
> [e-mail] writes:
> 
> > Given an iterator method, how can I get the results expressed as an
> > array? I could do:
> > 
> >   result = []
> >   iteratorMethod { |i| result << i }
> 
> If your iterator is defined on a collection includes Enumerable
> (eg. Array), you can use --- what is one subject these days ---
> Enumerable#collect.  Or you prefer a method like Array#filter for its
> effectiveness.
> 
> # Or do I miss the point?

Say I have a method which generates Fibonacci numbers to to a limit:

  def fibUpTo(max)
    i1, i2 = 1, 1
    while i1 <= max
      yield i1
      i1, i2 = i2, i1+i2
    end
  end

I can do something like

 result = []
 fibUpTo(20) { |f| result << f }

to collect the results into an array. However, to use Enumerable,
wouldn't I have to wrap it all in a class?

 class FibGen
   include Enumerable
   def initialize(max)
     @max = max
   end
   def each
    i1, i2 = 1, 1
    while i1 <= @max
      yield i1
      i1, i2 = i2, i1+i2
    end
  end
 end

 result = FibGen.new(20).collect

This just seems like a lot of work (he said, lazily). It would be nice 
to be able to use the iterator method directly to achieve the same
thing.


Dave