From: Terje Tjervaag <flecktone@...>
Date: 2005-10-26T19:56:07+09:00
Subject: sort on multiple attributes

Hi,

Just thought I'd write this to the list, since it wasn't immediately
obvious to me how to do it and I couldn't find it written anywhere on
the web..

Say you have an array of these music tracks:
Track = Struct.new("Track", :name, :artist, :album, :track_number)

..and you want to sort the array first by artist, then by album within
that artist and finally by track number within the album, this can
still be done by a pretty neat sort block:

sorted_tracks = tracks.sort do |a,b|
    if a.artist != b.artist
        a.artist <=> b.artist
    elsif a.album != b.album
        a.album <=> b.album
    else
        a.track_number.to_i <=> b.track_number.to_i
    end
end

--
Terje