Decorator(装饰器)

|--Decorator(装饰器)

eg:	
	def is_prime(num):
			if num < 2:
				return False
			elif num == 2:
				return True
			else:
				for i in range(2, num):
					if num % i == 0:
						return False
			return True
			
	def prime_nums():
		for i in range(2, 10000):
			if is_prime(i):
				print(i)
	代码混乱, 可读性差

use decorator
eg:
	import time

	def display_time(func):
		def wrapper(*args):
			t1 = time.time()
			result = func(*args)
			t2 = time.time()
			print("Total time: {:.4} s".format(t2 - t1))
			return result
		return wrapper

	def is_prime(num):
		if num < 2:
			return False
		elif num == 2:
			return True
		else:
			for i in range(2, num):
				if num % i == 0:
					return False
		return True

	@display_time
	def count_prime_nums(maxnum):
		count = 0
		for i in range(2, maxnum):
			if is_prime(i):
				count = count + 1
		return count

	count = count_prime_nums(10000)
	print(count)