【高级技巧】增量同步：深比较diff只下发变化字段

local function diffTbl(old, new, out)
    out = out or {}
    for k, v in pairs(new) do
        local ov = old[k]
        if type(v) == "number" and type(ov) == "number" then
            if math.abs(v - ov) > 0.001 then
                out[k] = v
            end
        elseif v ~= ov then
            out[k] = v
        end
    end
    return out
end

local snapshots = {}
local function pushPanel(actor)
    actor = getplayerbyname(actor)
    local newState = {
        atk = 3250, hp = 18700, belt = 1, title = "沙巴克功勋",
    }
    local old = snapshots[actor] or {}
    local changes = diffTbl(old, newState)
    local n = 0
    for _ in pairs(changes) do
        n = n + 1
    end
    if n > 0 then
        sendmsg(actor, 1, "属性变更 " .. n .. " 项，增量下发。")
        snapshots[actor] = newState
    end
end