Factory line limiter

 -- drafter.lua -- factory approach

local drafter = {}

function drafter.line(maxLength)
    return function(startX, startY, endX, endY)
        local deltaX, deltaY = endX - startX, endY - startY
        local requestedLength = math.sqrt(deltaX * deltaX + deltaY * deltaY)
        if requestedLength > maxLength then
            local ratio = maxLength / requestedLength
            endX, endY = startX + deltaX * ratio, startY + deltaY * ratio
        end
        display.newLine(startX, startY, endX, endY)
    end
end

return drafter