List_entry.rb

URI.open(url) do |uri|
      base_uri = uri.base_uri

      listable_type = case base_uri.to_s
      when /soundcloud.com\/(?<artist>.+)\/tracks/
        raise UnparsableTrackUrlError
      when /soundcloud.com\/(?<artist>.+)\/sets\/(?<title>.+)/
        SoundCloudPlaylist
      when /soundcloud.com\/(?<artist>.+)\/(?<title>.+)/
        SoundCloudTrack
      when /https?:\/\/(?<artist>.+)\.bandcamp.com\/track\/(?<title>.+)/
        BandcampTrack
      when /https?:\/\/(?<artist>.+)\.bandcamp.com\/album\/(?<title>.+)/
        BandcampAlbum
      end

      new listable: listable_type.new, url: base_uri, list: list, artist: $1, title: $2
    end