Lua计数器表：分类累加的统计模式

-- 错误：每类一个变量，新类型就要改代码
local drug, material, scroll = 0, 0, 0
for _, it in ipairs(items) do
    if it.type == "drug" then
        drug = drug + 1
    end
end

local counts = {}
for _, it in ipairs(items) do
    counts[it.type] = (counts[it.type] or 0) + 1
end
local parts = {}
for k, v in pairs(counts) do
    parts[#parts + 1] = k .. ":" .. v
end
local label = panel:getChildByName("statText")
label:setString(table.concat(parts, "  "))