【框架设计】事件总线：订阅优先级与异常隔离的调度设计

local bus = {}
local function subscribe(event, handler, prio)
    bus[event] = bus[event] or {}
    local list = bus[event]
    local item = { fn = handler, p = prio or 3 }
    local pos = #list + 1
    for i, e in ipairs(list) do
        if e.p < item.p then
            pos = i
            break
        end
    end
    table.insert(list, pos, item)
end

local function publish(event, ctx)
    for _, item in ipairs(bus[event] or {}) do
        local ok, err = pcall(item.fn, ctx)
        if not ok then
            setsysvar("BUS_ERR_" .. event, tostring(err))
        end
    end
end
subscribe("killmon", function(ctx) awardExp(ctx.actor) end, 1)
subscribe("killmon", function(ctx) rollDrop(ctx.actor) end, 2)