装饰器02
目录
1 装饰器的语法糖
1.1 定义
为了简洁而优雅地使用装饰器，Python提供了专门的装饰器语法来取代index=timer(index)的形式，需要在被装饰对象的正上方单独一行添加@timer,当解释器解释到@timer时就会调用timer函数，且把它正下方的函数名当做实参传入，然后将返回的结果重新赋值给原函数名
1.2 基本使用
import time
def timmer(f):
def wrapper(*args, **kwargs):
start = time.time()
res = f(*args, **kwargs)
stop = time.time()
print('run time is %s' % (stop - start))
return res
return wrapper
@timmer # index = timmer(index)
def index():
time.sleep(1)
print('from index')
@timmer # home = time(home)
def home(name):
time.sleep(2)
print('welcome to %s' % name)
return 123
index()
res = home("ccc")
print(res)
# from index
# run time is 1.0003390312194824
# welcome to ccc
# run time is 2.0008108615875244
# 123
2 有参装饰器
2.1 基本用法
@auth(driver='file')
def index():
pass
@auth(driver='mysql')
def home():
pass
2.2 示例
import time
def login(x, engine='file'):
def auth(func):
def wrapper(*args, **kwargs):
print("========>", x)
inp_user = input("username>>>>:").strip()
inp_pwd = input("password>>>:").strip()
if engine == "file":
print("基于file认证")
if inp_user == "egon" and inp_pwd == "123":
print('login successful')
res = func(*args, **kwargs)
return res
else:
print('username or password error')
elif engine == 'mysql':
print("基于mysql认证")
elif engine == "ldap":
print("基于ldap认证")
else:
print("未知认证来源")
return wrapper
return auth
@login(11, engine='file') # @auth # index = auth(index) # index=wrapper
def index():
time.sleep(1)
print('from index')
@login(22, engine='file') # @auth # home=auth(home) # home=wrapper
def home(name):
time.sleep(2)
print('home page,welcome %s' % name)
return 123
index()
home('egon')
# ========> 11
# username>>>>:egon
# password>>>:123
# 基于file认证
# login successful
# from index
# ========> 22
# username>>>>:egon
# password>>>:123
# 基于file认证
# login successful
# home page,welcome egon
3叠加多个装饰器
3.1 基本用法
@deco3
@deco2
@deco1
def index():
pass
# 本质
index=deco3(deco2(deco1(index)))
3.2 示例
def outter1(func1): # func1 = wrapper2的内存地址
print('============>outter1')
def wrapper1(*args, **kwargs):
print('=============wrapper1')
res1 = func1(*args, **kwargs)
return res1
return wrapper1
def outter2(func2): # func2 = wrapper3的内存地址
print('============>outter2')
def wrapper2(*args, **kwargs):
print('=============wrapper2')
res2 = func2(*args, **kwargs)
return res2
return wrapper2
def outter3(func3): # func3 = index的内存地址
print('============>outter3')
def wrapper3(*args, **kwargs):
print('=============wrapper3')
res3 = func3(*args, **kwargs)
return res3
return wrapper3
# index = wrapper1的内存地址
@outter1 # outter1(wrapper2的内存地址)-->wrapper1的内存地址
@outter2 # outter2(wrapper3的内存地址)-->wrapper2的内存地址
@outter3 # outter3(index的内存地址)-->wrapper3的内存地址
def index():
print('from index')
print('*'*25)
# print(index)
index()
# ============>outter3
# ============>outter2
# ============>outter1
# *************************
# =============wrapper1
# =============wrapper2
# =============wrapper3
# from index
import time
def timmer(func):
def wrapper1(*args, **kwargs):
start = time.time()
res = func(*args, **kwargs)
stop = time.time()
print('run time is:%s' % (stop - start))
return res
return wrapper1
def login(x, engine='file'):
def auth(func):
def wrapper2(*args, **kwargs):
print("========>", x)
inp_user = input("username>>>>:").strip()
inp_pwd = input("password>>>:").strip()
if engine == "file":
print("基于file认证")
if inp_user == "egon" and inp_pwd == "123":
print('login successful')
res = func(*args, **kwargs)
return res
else:
print('username or password error')
elif engine == 'mysql':
print("基于mysql认证")
elif engine == "ldap":
print("基于ldap认证")
else:
print("未知认证来源")
return wrapper2
return auth
# 场景一
@timmer
@login(11, engine='file')
def index():
time.sleep(1)
print('from index')
index()
# ========> 11
# username>>>>:egon
# password>>>:123
# 基于file认证
# login successful
# from index
# run time is:9.147817134857178
# 场景二
@login(11, engine='file')
@timmer
def index():
time.sleep(1)
print('from index')
index()
# ========> 11
# username>>>>:egon
# password>>>:123
# 基于file认证
# login successful
# from index
# run time is:1.0001623630523682
4 wraps装饰器
4.1 定义
- functools模块下提供一个装饰器wraps专门用来帮我们保留原函数的文档和函数名属性，修正装饰器
4.2 示例
import time
from functools import wraps
def timmer(func):
@wraps(func)
def wrapper(*args, **kwargs):
start = time.time()
res = func(*args, **kwargs)
stop = time.time()
print('run time is:%s' % (stop - start))
return res
return wrapper
@ timmer
def index():
"""index函数"""
time.sleep(1)
print('from index')
help(index)
5 匿名函数
"""
def func(x, y): # func=函数的内存地址
return x+y
匿名函数:没有名字的函数
应用场景:临时用一次，通常用于与其他函数配合使用
"""
# 无用调用方式
f = lambda x, y: x+y
print(f)
res = f(1, 2)
print(res)
# 调用方式1
res = (lambda x, y: x+y)(1, 2)
print(res)
# 调用方式2
salaries = {
"egon": 1000,
"alex": 2000,
"jack": 3000,
"rose": 4000
}
# 求薪资最高的那个人的名字
def get_salary(name):
return salaries[name]
print(max(salaries, key = get_salary)) # rose
print(max(salaries, key=lambda name: salaries[name])) # rose
print(min(salaries, key=lambda name: salaries[name])) # egon
print(sorted(salaries)) # ['alex', 'egon', 'jack', 'rose']
print(sorted(salaries, key=lambda name: salaries[name])) # ['egon', 'alex', 'jack', 'rose']
print(sorted(salaries, key=lambda name: salaries[name], reverse=True)) # ['rose', 'jack', 'alex', 'egon']
# 返回绝对值
print(abs(-11)) # 11
print(abs(0)) # 0
print(abs(11)) # 11
# 如果是空或布尔值为真则返回True
print(all('')) # True
print(all([])) # True
print(all([11, 22, 333, 0])) # False
# 只要有一个值的布尔值为真就返回True
print(any('')) # False
print(any([])) # False
print(any([0, None, '', 1])) # True
print(any([0, None, ''])) # False
# ASCⅡ表:65-90 A-Z
print(chr(65)) # 数字->字母A
print(ord('A')) # 字母->数字65
print(chr(90)) # Z
# 进制转换
print(bin(11)) # 十进制->二进制 0b1011
print(oct(11)) # 十进制->八进制 0o13
print(hex(11)) # 十进制->十六进制 0xb
# 工厂函数
int
float
str
list
tuple
dict
set
bool
bytes
# 查看对象是否可调用
print(callable(len)) # True
# 面向对象重点
classmethod
staticmethod
setattr
getattr
delattr
hasattr
dir
exec
l = eval("[1, 2, 3]")
print(l[0]) # 1
with open('user1.txt', mode='wt', encoding='utf-8') as f:
dic = {"ccc": "123", "zzz": "456", "yyy": "789"}
f.write(str(dic))
with open('user1.txt', mode='rt', encoding='utf-8') as f:
data = f.read()
print(data, type(data)) # {'ccc': '123', 'zzz': '456', 'yyy': '789'} <class 'str'>
dic = eval(data)
print(dic["ccc"]) # 123