From: Dave Thomas <Dave@...>
Date: 2001-08-24T07:04:01+09:00
Subject: [ruby-talk:20213] Re: In Ruby 0 is true but nil is false.. or how to shoot yourself?..

Guillaume Cottenceau <gc@mandrakesoft.com> writes:

> I have a simple Audio-CD database (using CSV format). I was writing a
> piece of Ruby code to list what's in the DB. And actually I wanted to
> display the entries sorted by Artist and by Album.
> 
> 
> Originally, I wrote that:
> 
> db.sort { |a,b| a[1]['Artist'] <=> b[1]['Artist'] ||
>                 a[1]['Album'] <=> b[1]['Album'] }.each { |t|
>         ...
> }

Try 'nonzero?'

dave[~ 13:17:19] ri nonzero
------------------------------------------------------- Numeric#nonzero?
     num.nonzero? -> num or nil
------------------------------------------------------------------------
     Returns num if num is not zero, nil otherwise. This behavior is
     useful when chaining comparisons:
        a = %w( z Bb bB bb BB a aA Aa AA A )
        b = a.sort {|a,b| (a.downcase <=> b.downcase).nonzero? || a <=> b }
        b   #=> ["A", "a", "AA", "Aa", "aA", "BB", "Bb", "bB", "bb", "z"]



Regards


Dave