[ruby-talk:6613] Re: best way to interleaf arrays?

On Wed, 29 Nov 2000, Dave Thomas wrote:

> David Alan Black <[e-mail]> writes:
> 
> >    class Array 
> >      def to_h
> >        h = {}
> >        each_index { |i| h[i] = at i }
> >        h
> >      end
> >    end
> > 
> >    %w{ list of words }.to_h  # => {0=>"list", 1=>"of", 2=>"words"}
> > 
> > One could then invert the hash to get at least one version of the
> > original effect -- namely, the original array elements as hash keys
> > and all the values true.  (Even zero!)
> 
> I'm convinced by this, particular if we added the block form too.

I was wondering about a block form.  I'm not sure exactly what it
would do -- specifically, whether the results of the block would
pertain to the keys or the values of the new hash.  In other words,
would it be this:

      each_with_index { |e,i| h[i] = yield(i, e) }

or this:

      each_with_index { |e,i| h[yield(i, e)] = e }

or something else?  Or might it be better for to_h to be blockless,
since the new hash could in any case simply be processed with all the
familiar iterators?

Another question on the hypothetical to_h subject: would there be any
reason for to_h not to be part of Enumerable, rather than Array?


David

-- 
David Alan Black
home: [e-mail]
work: [e-mail]
Web:  http://pirate.shu.edu/~blackdav