装饰器，其实是用到了闭包的原理来进行操作的。
单个装饰器：
以下是一个简单的例子：
def outer(func):
print("OUTER enter ...")
def wrapper(*args, **kwargs):
print("调用之前......")
result = func(*args, **kwargs)
print("调用之后......")
return result
print("OUTER leave ...")
return wrapper
@outer
def my_hello():
print("hello world")
上面的代码可以运行出结果：
这个时候就会把这个闭包创建出来。
当我们调用my_hello函数的时候，会进行执行wrapper里的代码：
def outer(func):
print("OUTER enter ...")
def wrapper(*args, **kwargs):
print("调用之前......")
result = func(*args, **kwargs)
print("调用之后......")
return result
print("OUTER leave ...")
return wrapper
@outer
def my_hello():
print("hello world")
my_hello()
调用原理：
等价于：
def outer(func):
print("OUTER enter ...")
def wrapper(*args, **kwargs):
print("调用之前......")
result = func(*args, **kwargs)
print("调用之后......")
return result
print("OUTER leave ...")
return wrapper
# @outer
def my_hello():
print("hello world")
my_hello = outer(my_hello)
my_hello()
多重装饰器修饰：
def outer1(func):
print("OUTER enter ...1")
def wrapper(*args, **kwargs):
print("调用之前......1")
result = func(*args, **kwargs)
print("调用之后......1")
return result
print("OUTER leave ...1")
return wrapper
def outer2(func):
print("OUTER enter ...2")
def wrapper(*args, **kwargs):
print("调用之前......2")
result = func(*args, **kwargs)
print("调用之后......2")
return result
print("OUTER leave ...2")
return wrapper
@outer1
@outer2
def my_hello():
print("hello world")
打印的结果如下：
调用的时候：
def outer1(func):
print("OUTER enter ...1")
def wrapper(*args, **kwargs):
print("调用之前......1")
result = func(*args, **kwargs)
print("调用之后......1")
return result
print("OUTER leave ...1")
return wrapper
def outer2(func):
print("OUTER enter ...2")
def wrapper(*args, **kwargs):
print("调用之前......2")
result = func(*args, **kwargs)
print("调用之后......2")
return result
print("OUTER leave ...2")
return wrapper
@outer1
@outer2
def my_hello():
print("hello world")
my_hello()
运行结果为：
调用原理：
def outer1(func):
print("OUTER enter ...1")
def wrapper(*args, **kwargs):
print("调用之前......1")
result = func(*args, **kwargs)
print("调用之后......1")
return result
print("OUTER leave ...1")
return wrapper
def outer2(func):
print("OUTER enter ...2")
def wrapper(*args, **kwargs):
print("调用之前......2")
result = func(*args, **kwargs)
print("调用之后......2")
return result
print("OUTER leave ...2")
return wrapper
# @outer1
# @outer2
def my_hello():
print("hello world")
my_hello = outer2(my_hello)
my_hello = outer1(my_hello)
my_hello()
运行结果如下：
