我需要知道为什么这个代码的输出是sayhello()only？
def myDecorator(func): # Decorator
def nestedfunc(): # Any Name Its Just For Decoration
print("Before") # Message From Decorator
func() # Execute Function
print("After") # Message From Decorator
return nestedfunc # Return All Data
def sayHello():
print("Hello from sayHello function")
myDecorator(sayHello())
myDecorator(sayHello())次调用sayHello()返回None，then次调用myDecorator(None)返回nestedfunc，实际上没有被调用.
使用以下方法修饰函数并调用它:
def myDecorator(func):
def nestedfunc():
print("Before")
func()
print("After")
return nestedfunc
@myDecorator # correct decorator syntax
def sayHello():
print("Hello from sayHello function")
sayHello()
输出:
Before
Hello from sayHello function
After
decorator(@)语法等价于以下内容:
def myDecorator(func):
def nestedfunc():
print("Before")
func()
print("After")
return nestedfunc
def sayHello():
print("Hello from sayHello function")
# Pass sayHello as the func parameter to MyDecorator
# and return nestedfunc. Reassign to sayHello.
sayHello = myDecorator(sayHello)
sayHello() # now really calling nestedfunc.