1. Application of the function name.
Function name is a variable, but it is a special variable, and can be performed with parentheses variable function.
1. The memory address of the function name
DEF FUNC ():
Print ( " Oh " )
Print (FUNC)
# result: <function func at 0x1101e4ea0>
2. The function name can be assigned to other variables
DEF func ():
Print ( " Oh " )
Print (FUNC)
A = FUNC # to function as a variable to another variable
A () # function call func ()
3. The element name can be used as containers of
DEF func1 ():
Print ( " Oh " )
DEF func2 ():
Print ( " Oh " )
DEF func3 ():
Print ( " Oh " )
DEF Func4 ():
Print ( " Oh " )
LST = [func1, func2 , func3]
for i in LST:
i ()
4. The name can be used as parameters of the function
DEF FUNC ():
Print ( " eat it " )
DEF func2 (the Fn):
Print ( " I am func2 " )
the Fn () # execute pass over the Fn
Print ( " I am func2 " )
func2 (FUNC) # put parameters passed to the function func as func2 parameter fn.
The name can be used as the return value of the function
DEF func_1 ():
Print ( " this is a function. 1 " )
DEF func_2 ():
Print ( " this is a function 2 " )
Print ( " this is a function. 1 " )
return func_2
Fn = func_1 () # executes the function 1. Function 2 is a function of a return, this time point is above fn 2 function
fn () # perform the above function returns
2. Closure
What is a closure? Closures is a reference to the inner function, variable external layer function (non-global). Called closures
def outer():
a = 10 # 很耗时
def inner():
print(a)
return inner
# outer()()
# outer()()
ret = outer()
ret()
ret()
注意：我们可以使用__closure__来检测函数是否是闭包. 使用函数名.__closure__返回cell就是闭包. 返回None就不是闭包
def func1(): name = "disman" def func2(): print(name) # 闭包 func2() print(func2.__closure__) # (<cell at 0x10c2e20a8: str object at 0x10c3fc650>,)
func1()
闭包好处:
1. 保护变量
2. 可以让一个变量常驻内存
3. 迭代器
__iter__() 可迭代对象. 获取迭代器
__next__() + __iter__() 迭代器
特点:
1. 惰性机制
2. 只能向前
3. 节省内存
for循环的内部就是迭代器
lst = [1,2,4]
it = lst.__iter__() # 获取迭代器
while 1:
try:
it.__next__() # 从迭代器中获取数据
except StopIteration:
break
Iterable: 可迭代的
Iterator: 迭代器