The following two snippets are semantically identical
[code 1]
def deco1(func):
print "before"
func()
print "after"
def func():
print "in func"
if __name__ == '__main__':
print "--------------"
deco1(func)
print "=============="[code 2]
def deco1(func):
def _wrap():
print "before"
func()
print "after"
return _wrap
@deco1
def func():
print "in func"
if __name__ == '__main__':
print "--------------"
func()
print "=============="output
--------------
before
in func
after
==============2.Decorator with parameters
The following two snippets are semantically identical
[code 3]
def deco1(receive_deco1_param):
def _wrap(receive_function_name):
def __wrap(receive_function_param):
print "deco1's param is " + receive_deco1_param
print "before"
receive_function_name(receive_function_param)
print "after"
return __wrap
return _wrap
def func(p):
print "func's param is " + p
if __name__ == '__main__':
print "--------------"
deco1("deco1 param")(func)("func param")
print "=============="[code 4]
def deco1(receive_deco1_param):
def _wrap(receive_function_name):
def __wrap(receive_function_param):
print "deco1's param is " + receive_deco1_param
print "before"
receive_function_name(receive_function_param)
print "after"
return __wrap
return _wrap
@deco1("deco1 param")
def func(p):
print "func's param is " + p
if __name__ == '__main__':
print "--------------"
func("func param")
print "=============="output
--------------
deco1's param is deco1 param
before
func's param is func param
after
==============3.The best practice of decorator maybe
[code 5]
from functools import wraps
def deco1(receive_deco1_param):
def _wrap(receive_function_name):
@wraps(receive_function_name)
def __wrap(receive_function_param):
print "deco1's param is " + receive_deco1_param
print "before"
receive_function_name(receive_function_param)
print "after"
return __wrap
return _wrap
@deco1("deco1 param")
def func(p):
print "func's param is " + p
if __name__ == '__main__':
print "--------------"
func("func param")
print func.__name__
print "=============="In code 4,if print func.__name__ in main, output will be __wrap,but in code 5,the output is func.
4.Class Decorator
The semantics and design goals of class decorators are the same as for function decorators; the only difference is that you’re decorating a class instead of a function.
[reference]
1.pep-0318
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