From: pharrington <xenogenesis@...>
Date: 2009-12-25T02:50:06+09:00
Subject: Re: "No block given" error -- spurious?

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.rb(with
> 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.