AppleScript to get iTunes to sort albums by release date

AlbumsOrder.scpt

-- Fix albums display order
-- Changes the "sort album" field, to ensure that albums get displayed in chronological order on iPods.
-- CC-BY-NC 2011, Jean-Karim Bockstael, 
tell application "iTunes"
    -- input checking
    if selection is {} then
        display dialog "You must select at least a track"
        return
    else
        set selected_tracks to selection
        repeat with a_track in selected_tracks
            if a_track's album = "" then
                display dialog "All tracks must have their Album field filled"
                return
            end if
            if a_track's year = "" then
                display dialog "All tracks must have their Year field filled"
                return
            end if
        end repeat
        if length of selected_tracks > 1 then
            set cur_album to album of item 1 of selected_tracks
            set cur_year to year of item 1 of selected_tracks
            repeat with a_track in selected_tracks
                if a_track's album is not equal to cur_album then
                    display dialog "All tracks must share the same album name"
                    return
                end if
                if a_track's year is not equal to cur_year then
                    display dialog "All tracks must share the same release year"
                    return
                end if
                set cur_album to a_track's album
                set cur_year to a_track's year
            end repeat
        end if
        -- actual work
        repeat with a_track in selected_tracks
            set a_track's sort album to (a_track's year as string) & " " & (a_track's album as string)
        end repeat
    end if
end tell