【高级技巧】桥接模式：两个维度的独立扩展封装

local ELEMENTS = {
    fire = function(dmg) return dmg * 1.2 end,
    ice = function(dmg) return dmg * 0.8 + 50 end
}
local SHAPES = {
    single = function(dmg, targets)
        return { { targets[1], dmg } }
    end,
    aoe = function(dmg, targets)
        local out = {}
        for _, t in ipairs(targets) do
            out[#out + 1] = { t, dmg }
        end
        return out
    end
}

local function castSkill(elem, shape, dmg, targets)
    return SHAPES[shape](ELEMENTS[elem](dmg), targets)
end
print(#castSkill("fire", "aoe", 100, { "怪1", "怪2", "怪3" }))