Closure

What is a closure ?
A closure is an internal function defined in an external function , Internal functions refer to variables in external functions , The return value of the external function is the internal function
A closure is an entity composed of a function and its associated reference environment ( namely ： Closure = function + Citation environment )
The characteristics of closures ?

	 Nested function 
	 The inner function refers to the variable of the outer function 
	 Take the inner function as the return value of the outer function 

Define closure , The completed functions are : Pass in a number, sum it and output
for example : Pass in 10 -> Output 10
Pass in 15 -> Output 25
Pass in 20 -> Output 45

def outer():
    sum1 = 0

    def inner(num):
        nonlocal sum1
        sum1 = sum1 + num
        return sum1

    return inner


inner = outer()
print(inner(10))
print(inner(15))
print(inner(20))

2. Define a decorator ： Print the time taken for the function to run

You get a time before execution
Execute function
Get a time after executing the function
To find the time difference
time modular

def outer(func):

    def inner(*args):
        data1 = time.time()
        func(*args)
        data2 = time.time()
        print(data2 - data1)
    return inner


@outer
def print_info(arg1):
    print(arg1)


print_info([i for i in range(1000)])

Define a class ：

requirement ： Contains an object property , And use _( Underline ) Named
Define a class method ( Decorator )
Define a static method ( Decorator )
Define delegate properties ( Three class decorators ): You can visit _ The value of the named attribute
You can modify _ The value of the named attribute
You can delete _ Named properties
perform ：
Instance an object
Calling class methods ( Class and object )
Call static methods ( Class and object )
object . Delegate properties
object . Delegate properties = value
del object . Delegate properties

class Person:
    def __init__(self, name, age, sex):
        self._name = name
        self.age = age
        self.sex = sex

    @staticmethod
    def run():
        print(' Assad is ')

    @classmethod
    def lack(cls):
        print(cls)

    def get_item(self):
        return self._name

    def set_item(self, value):
        self._name = value

    def del_item(self):
        del self._name

    name = property(get_item, set_item, del_item)


per = Person(" Wang XX ", 60, ' male ')
per.run()
Person.run()
per.lack()
Person.lack()
print(per.name)
per.name = 123
print(per.name)
del per.name
print(per.name)