写在最前：博主最近想搞django源码，发现好多搞不明白。干脆重新康康。大概是2022年初开始的python的学习，好多其实明白的很浅。重新巩固基础，博主水平不高，不敢好为人师。个人的经验就是一定要少看多写
函数嵌套：
举例子：
name = "g2"
def run():
name = "nico"
def inner():
print(name)
return inner
hooxi = run()
hooxi()结果是nico
如果注释，则是g2
name = "g2"
def run():
name = "nico"
def inner():
print(name)
return [inner, inner, inner]
data_list = run()
data_list[1]()
data_list[2]()C:\Users\admin\AppData\Local\Programs\Python\Python310\python.exe D:/Code/pycharm/python的基础进阶/嵌套.py nico nico
进程已结束,退出代码0
- 总结:
- 优先在自己的作用域找，没有就去上级作用域。
- 在作用域中寻找值时，要确保此次此刻值
- 分析函数的执行，并确定函数作用域链
闭包：
将数据封装在一个包（区域）中，使用时再去里面取。
博主此次回顾的时候觉得这个思想很厉害
比如:
def run(arg):
def inner():
print(arg)
return inner
v1 = run(55)
v2 = run("monsey")
v1()
v2()比如搞一个爬虫， 搞梨视频：
装饰器：
比如：
def outer(origin):
def inner():
print("g2")
res = origin()
print("choke")
return res
return inner
@outer
def run1():
print("粉丝")
value = (1, 2, 3, 4)
return value
@outer
def run2():
print("观众")
value = (6, 7, 8, 9)
return value
run1()
run2()g2 粉丝 choke g2 观众 choke、
使用闭包多线程pa视频：
import requests
from concurrent.futures.thread import ThreadPoolExecutor
def download_video(url):
contId = url.split("_")[1]
videoStatusUrl = f"https://www.pearvideo.com/videoStatus.jsp?contId={contId}"
headers = {
"User-Agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/88.0.4324.192 Safari/537.36",
"Referer": url
}
resp = requests.get(videoStatusUrl, headers=headers)
dic = resp.json()
srcUrl = dic['videoInfo']['videos']['srcUrl']
systemTime = dic['systemTime']
srcUrl = srcUrl.replace(systemTime, f"cont-{contId}")
return requests.get(srcUrl).content
def outer(file_name):
def write_file(response):
content = response.result()
with open(file_name, mode='wb') as file_object:
file_object.write(content)
return write_file
POOL = ThreadPoolExecutor(10)
video_dict = {
("拾荒老人.mp4", "https://www.pearvideo.com/video_1731984"),
("宝妈脱口秀.mp4", "https://www.pearvideo.com/video_1731984"),
("古德伍德.mp4", "https://www.pearvideo.com/video_1784888"),
("大爷理发.mp4", "https://www.pearvideo.com/video_1502023"),
("七旬老翁.mp4", "https://www.pearvideo.com/video_1501101")
}
for item in video_dict:
future = POOL.submit(download_video, url=item[1])
future.add_done_callback(outer(item[0]))
POOL.shutdown()download_url要进行防盗链的处理
匿名函数：
func = lambda x: [x * i for i in range(1, 10)]
v1 = func(5)
print(v1)或者：
func = lambda x: "g了" if x <= 15 else "赢了"
v1 = func(5)
print(v1)
v2 = func(16)
print(v2)生成器：
生成器函数，但函数中有yield存在时，这个函数就是生产生成器函数。
生成器对象，执行生成器函数时，会返回一个生成器对象
def func():
print(123)
yield 1
print(555)
yield 2
print(666)
yield 3
data = func()
v1 = next(data)
print(v1)
v2 = next(data)
print(v2)
v3 = next(data)
print(v3)应用：
import random
def func():
count = 0
while count < 999:
count = count + 1
yield random.randint(1000, 9999)
data = func()
v1 = next(data)
print(v1)
v2 = next(data)
print(v2)推导式：
num_list = [i for i in range(10)]
print(num_list)
num_set = {i for i in range(10)}
print(num_set)
num_dict = {i: i for i in range(10)}
print(num_dict)
# 元组, 不会立刻执行，而是得到一个生成器
num_tuple = (i for i in range(10))
print(num_tuple)
for item in num_tuple:
print(item)比较：
列表：
def num():
return [lambda x: i * x for i in range(4)]
result = [m(2) for m in num()]
print(result)元组：
def num():
return (lambda x: i * x for i in range(4))
result = [m(2) for m in num()]
print(result)未完待续
