From: Morton Goldberg <m_goldberg@...>
Date: 2007-09-12T14:39:44+09:00
Subject: Re: undefined method `+' for nil:NilClass (NoMeth

On Sep 11, 2007, at 8:04 PM, Rob wrote:

> I have corrected the class code,
>
> # This version includes the enumerable module, gaining access  
> to .collect .inject .each_with_index et al.
> class Generator
>    include Enumerable
>
>    def initialize(start="a", limit=52)
>        @limit = limit
>        @start = start
>    end
>
>    def each
>        # Dup here otherwise another call to .each later on starts  
> from where this left off
>        char = @start.dup                    @limit.times do
>            # And dup here otherwise the values returned will point  
> to the same location
>            # and .collect would return ["ba", "ba", "ba", ... "ba"]  
> or whatever the last
>            # character sequence was.
>            yield char.dup
>            char.succ!
>        end
>    end
> end
>
> gen = Generator.new
>
> gen.each { |char| puts char }
>
> # comma separated string
> puts gen.inject { |memo, s| "#{memo},#{s}" }
>
> # returns array of codes
> puts gen.collect

It seems to me that you are reinventing the wheel -- in this case  
'wheel' being the built-in class Range. Why not do it like this?

('a'..'az').each { |chr| puts chr }

('a'..'az').to_a.join(', ') # => "a, b, c, d, e, f, g, h, i, j, k, l,  
m, n, o, p, q, r, s, t, u, v, w, x, y, z, aa, ab, ac, ad, ae, af, ag,  
ah, ai, aj, ak, al, am, an, ao, ap, aq, ar, as, at, au, av, aw, ax,  
ay, az"

('a'..'az').to_a # => ["a", "b", "c", "d", "e", "f", "g", "h", "i",  
"j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w",  
"x", "y", "z", "aa", "ab", "ac", "ad", "ae", "af", "ag", "ah", "ai",  
"aj", "ak", "al", "am", "an", "ao", "ap", "aq", "ar", "as", "at",  
"au", "av", "aw", "ax", "ay", "az"]

Regards, Morton