【高级技巧】事件委托表：事件与处理函数解耦注册

local events = {}
local function onEvent(name, fn)
    events[name] = events[name] or {}
    table.insert(events[name], fn)
end
local function fireEvent(name, actor, data)
    local fns = events[name]
    if fns == nil then return end
    for _, fn in ipairs(fns) do
        local ok, err = pcall(fn, actor, data)
        if not ok then
            sendmsg(nil, 1, "事件异常：" .. tostring(err))
        end
    end
end

onEvent("player_login", function(actor, data)
    sendmsg(actor, 1, "欢迎回来，" .. tostring(data.name))
end)
onEvent("player_login", function(actor, data)
    fireEvent("check_mail", actor, data)
end)