From: RichardOnRails <RichardDummyMailbox58407@...>
Date: 2009-12-25T03:05:05+09:00
Subject: Re: "No block given" error -- spurious?

On Dec 24, 12:47 pm, pharrington <xenogene...@gmail.com> wrote:
> On Dec 24, 12:08 pm, "Richard Lionheart" <No...@Nowhere.net> wrote:
>
> > The code below, found athttp://github.com/eregon/RPCFN4/blob/master/solutions/benoit_daloze.r...
> > the last two lines added for testing it) produced the error:
> > Polynomials.rb:15:in `each_with_index': no block given (LocalJumpError)
> > The erronious line is flagged with #=================
> > Debugging indicates that @ceof is an Array.
> > What's up?
>
> > # Benoit Daloze
> > # Ruby Programming Challenge For Newbies #4
> > # pretty-print polynomials
> > #
> > # My solution use Enumerable#inject to build the String,
> > # with every "monomial" splitted in 3 parts : sign, coefficient and variable
> > class Polynomial
> >   def initialize(coef)
> >     raise ArgumentError, "Need at least 2 coefficients" if coef.size < 2
> >     @coef = coef
> >   end
>
> >   def to_s
> >     return '0' if @coef.all? { |c| c == 0 }
> >     @coef.each_with_index.inject("") { |s, (coef, i)|   #
> > <===================================
> >       pow = @coef.length-1-i
> >       if coef == 0
> >  s
> >       else
> >  s +
> >  (coef > 0 ? '+' : '-') + # sign
> >  (coef.abs == 1 && pow != 0 ? '' : coef.abs.to_s) + # coef
> >  (pow < 2 ? 'x'*pow : "x^#{pow}") # var
> >       end
> >     }.sub(/^\+/, "")
> >   end
> > end
>
> >  p = Polynomial.new( [1, 2] )
> >  puts p
>
> > --- news://freenews.netfront.net/ - complaints: n...@netfront.net ---
>
> This should work with Ruby 1.9, as each_with_index returns an
> Enumerator when called without a block. Ruby 1.8's each_with_index,
> however, requires a block to be passed to it.

Thanks a lot.  And I apologize for not mentioning that I was running
1.8.6.