Lua迭代器

function list_iter(t)
    local i=0
    local n=table.getn(t)
    return function()
        i=i+1
        if i<=n then return t[i] end
    end
end

t={10,20,30}
for elem in list_iter(t) do
    print(elem)
end

for var_1,...,var_n in explist do block end
--等价于
do
    local _f ,_s,_var=explist--返回迭代函数、状态常量、控制变量
    while true do
        local var_1,...,var_n =_f(_s,_var)
        _var=var_1
        if _var==nil then break end
        block
    end
end