lua table的一个排序算法

lines = {

    luaH_set = 10,

    luaH_get = 24,

    luaH_present = 48,

}

function pairsByKeys (t, f)

    local a = {}

    for n in pairs(t) do table.insert(a, n) end

    table.sort(a, f)

    local i = 0                 -- iterator variable

    local iter = function ()    -- iterator function

       i = i + 1

       if a[i] == nil then return nil

       else return a[i], t[a[i]]

       end

    end

    return iter

end

f=function(a,b)
if a > b then return true end
end

for name, line in pairsByKeys(lines,f) do

    print(name, line)

end