如何解决在mixin类中声明装饰器方法
我已经写了一个这样的课程:
class AbstractBigHandler(AbstractHandler,ActionTimer):
def __init__(self,path,data_container):
AbstractHandler.__init__(self)
ActionTimer.__init__(self,data_container)
@time_action
def handle(self,request):
# Do something
我想在其中放置handle()方法,所以我想到了一个编写mixin类的想法,该类将在其中提供一个装饰器类,因为在我看来,它将在码。而且,我希望这个mixin类可用于以后将要写的其他类:
class ActionTimer:
def __init__(self,data_container):
self.data_container = data_container
self.class_name = self.__class__.__name__
def time_action(self,func):
def wrapper(self,func,*args,**kwargs):
start_time = datetime.now()
func_output = func.handle(args,kwargs)
end_time = datetime.now()
execution_time = end_time - start_time
print(self.__class__.__name__," execution time: ",execution_time)
self.data_container.add_data(self.class_name,execution_time)
return func_output
return wrapper
其中的data_container参数只是我打算浮动的一个单例,并通过其字典属性(通过.add_data()方法)收集数据。
现在,当我尝试为AbstractBigHandler类运行测试时,它在实例化时立即失败,并显示以下错误堆栈:
C:\project\tests>python -m unittest test_abstract_big_handler
Traceback (most recent call last):
File "C:\Users\***\AppData\Local\Continuum\anaconda3\lib\runpy.py",line 193,in _run_module_as_main
"__main__",mod_spec)
File "C:\Users\***\AppData\Local\Continuum\anaconda3\lib\runpy.py",line 85,in _run_code
exec(code,run_globals)
File "C:\Users\***\AppData\Local\Continuum\anaconda3\lib\unittest\__main__.py",line 18,in <module>
main(module=None)
File "C:\Users\***\AppData\Local\Continuum\anaconda3\lib\unittest\main.py",line 100,in __init__
self.parseArgs(argv)
File "C:\Users\***\AppData\Local\Continuum\anaconda3\lib\unittest\main.py",line 147,in parseArgs
self.createTests()
File "C:\Users\***\AppData\Local\Continuum\anaconda3\lib\unittest\main.py",line 159,in createTests
self.module)
File "C:\Users\***\AppData\Local\Continuum\anaconda3\lib\unittest\loader.py",line 220,in loadTestsFromNames
suites = [self.loadTestsFromName(name,module) for name in names]
File "C:\Users\***\AppData\Local\Continuum\anaconda3\lib\unittest\loader.py",in <listcomp>
suites = [self.loadTestsFromName(name,line 154,in loadTestsFromName
module = __import__(module_name)
File "C:\project\tests\test_abstract_big_handler.py",line 5,in <module>
from project.common.handlers.AbstractBigHandler import AbstractBigHandler
File "C:\project\common\handlers\AbstractBigHandler.py",line 17,in <module>
class AbstractBigHandler(AbstractHandler,ActionTimer):
File "C:\project\common\handlers\AbstractBigHandler.py",line 69,in AbstractBigHandler
@time_action
NameError: name 'time_action' is not defined
我不确定为什么会发生这种情况-因为ActionTimer类是作为AbstractBigHandler类中的第二个继承类添加的,所以它的方法time_action()应该(并且当我使用PDB进行检查时)应该存在于AbstractBigHandler方法中
帮助?
解决方法
由于time_action
是修饰符,因此您无需在func
中再次传递wrapped
。由于容器是Singleton,因此您可以使用classmethod并直接引用它。
from datetime import datetime
import random
class AbstractHandler(object):
pass
class ActionTimer(object):
data_container = []
def __init__(self,data_container):
self.data_container = data_container
self.class_name = self.__class__.__name__
@classmethod
def time_action(cls,func):
def wrapper(*args,**kwargs):
start_time = datetime.now()
func_output = func(*args,**kwargs)
end_time = datetime.now()
execution_time = end_time - start_time
# just some random value to show results (remove)
execution_time = execution_time.total_seconds() + random.randrange(1,10,1)
print(cls.__name__," execution time: ",execution_time)
cls.data_container.append((cls.__name__,execution_time))
return func_output
return wrapper
class AbstractBigHandler(AbstractHandler,ActionTimer):
def __init__(self,path,data_container):
AbstractHandler.__init__(self)
ActionTimer.__init__(self,data_container)
@classmethod
@ActionTimer.time_action
def handle(cls,request):
print(request,"CONTAINER:",cls.data_container)
a = AbstractBigHandler("path",[])
for i in range(5):
a.handle("some-request-" + str(i))
print("FINAL:",ActionTimer.data_container)
产生以下内容:
some-request-0 CONTAINER: []
ActionTimer execution time: 9.0
some-request-1 CONTAINER: [('ActionTimer',9.0)]
ActionTimer execution time: 6.0
some-request-2 CONTAINER: [('ActionTimer',9.0),('ActionTimer',6.0)]
ActionTimer execution time: 9.0
some-request-3 CONTAINER: [('ActionTimer',6.0),9.0)]
ActionTimer execution time: 3.0
some-request-4 CONTAINER: [('ActionTimer',3.0)]
ActionTimer execution time: 5.0
FINAL: [('ActionTimer',3.0),5.0)]
,
不幸的是,继承的名称空间仅在完全定义了类主体之后 进行处理。像AbstractBigHandler
这样的子类在类定义时没有简单的方法引用其父类的属性。这个问题的简单得多的例子是:
class A:
foo = 1
class B(A): # inherit the foo class attribute
bar = foo + 1 # but looking it up here fails,with the same NameError you're seeing
要解决此问题,您将需要显式引用父类(例如,从A.foo
中引用B
),或者将要继承的值移出父类以成为全局变量变量。对于装饰器来说,这通常是最好的方法,需要在子类的定义时应用装饰器,而不是在将实例作为self
传递给方法时使用。
实际上,这是我在代码中看到的第二个问题,即装饰器具有一些混乱的参数(在装饰器本身以及内部的包装函数中)。我建议这样的结构:
class ActionTimer:
def __init__(self,data_container):
self.data_container = data_container
self.class_name = self.__class__.__name__
def time_action(func): # top-level function,no self arg here
def wrapper(self,*args,**kwargs): # no func arg here,but we *do* have a self arg
start_time = datetime.now()
func_output = func(self,args,kwargs) # don't call handle,*we're* handle!
end_time = datetime.now()
execution_time = end_time - start_time
print(self.__class__.__name__,execution_time)
self.data_container.add_data(self.class_name,execution_time)
return func_output
return wrapper
现在AbstractBigHandler
类将按您编写的方式工作。
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