接受函数作为参数的函数成为”高阶函数“
network = {
{name= "gramma", IP = "210.26.30.34"},
{name= "arrial", IP = "210.26.30.35"},
{name= "lua", IP = "210.26.30.36"},
{name= "cplus", IP = "210.26.30.37"},
{name= "dephi", IP = "210.26.30.38"},
}
以name字段来对table排序
table.sort(network, function (a,b) (a.name > b.name) end)
function derivative (f, delta)
delta = delta or 1e-4
return function (x)
return (f(x + delta) - f(x))/delta
end
end
闭合函数Closure
function newCounter()
local i = 0
return function ()
i = i + 1
return i
end
end
c1 = newCounter()
print(c1()) -->1
print(c1()) -->2
非全局函数
函数不仅可以存储在全局的变量中，还可以存储在table的字段和局部变量中
---[[
lib = {}
lib.foo = function (x, y) return x + y end
lib.goo = function (x, y) return x - y end
lib = {
foo = function (x, y) return x + y end
goo = function (x, y) return x - y end
}
lib = {}
function lib.foo (x, y) return x + y end
function lib.goo (x, y) return x - y end
--]]
--[[
function values (t)
local i = 0
return function () i = i + 1;
return t[i]
end
end
t= {10, 20, 30}
iter = values(t)
while true do
local element = iter()
if element == nil then break end
print(element)
end
--]]
--[[
function allwords ()
local line = io.read()
local pos = 1
return function ()
while line do
local s, e = string.find(line, "%w+", pos)
if s then
pos = e + 1
return sting.sub(line,s,e)
else
line = io.read()
pos = 1
end
end
return nil
end
end
for word in allwords() do
print(word)
end
--]]
