Lua unpack拆包：动态调用的参数展开

-- 错误：按参数个数手写分支，越写越炸
function cast(name, a, b, c)
    if name == "heal" then
        doHeal(a, b)
    elseif name == "dash" then
        doDash(a)
    end
end

local EFFECTS = {
    heal = function(amount, times)
        return "heal " .. amount .. "x" .. times
    end,
    dash = function(dist)
        return "dash " .. dist
    end,
}
local function cast(name, params)
    return EFFECTS[name](unpack(params))
end
local p = getplayerbyname("unp01")
sendmsg(p, 1, cast("heal", {120, 3}))