我编写了一个Python流控制框架,其工作原理与unittest.TestCase
非常相似:用户创建一个从框架类派生的类,然后编写自定义的task_*(self)
方法。框架发现并运行它们:
###################
# FRAMEWORK LIBRARY
###################
import functools
class SkipTask(BaseException):
pass
def skip_if(condition):
def decorator(task):
@functools.wraps(task)
def wrapper(self, *args, **kargs):
if condition(self):
raise SkipTask()
return task(self, *args, **kargs)
return wrapper
return decorator
class MyFramework(object):
def run(self):
print "Starting task"
try:
self.task()
except SkipTask:
print "Skipped task"
except Exception:
print "Failed task"
raise
else:
print "Finished task"
#############
# USER SCRIPT
#############
class MyUserClass(MyFramework):
skip_flag = True
@skip_if(lambda self: self.skip_flag)
def task(self):
print "Doing something"
if __name__ == '__main__':
MyUserClass().run()
输出:
^{pr2}$我想更改框架,这样每当@skip_if
的条件是True
,包装器就不会打印"Starting task"
。
我试过了,但没用:
def skip_if(condition):
def decorator(task):
print "decorating " + str(task)
task.__skip_condition = condition
return task
return decorator
class MyFramework(object):
def run(self):
try:
if self.task.__skip_condition():
print "Skipped task"
return
except AttributeError:
print str(self.task) + " is not decorated"
pass
print "Starting task"
try:
self.task()
except Exception as e:
print "Failed task: " + str(e)
raise
else:
print "Finished task"
输出:
decorating <function task at 0x194fcd70>
<bound method MyUserClass.task of <__main__.MyUserClass object at 0x195010d0>> is not decorated
Starting task
Doing something
Finished task
为什么没有跳过任务呢?在
您使用的是一个双下划线名称,它在
run
方法中经历了private name mangling。在单步执行调试器时,我得到:
不要在这里使用双下划线名称;如果将函数属性重命名为
^{pr2}$_skip_condition
,则代码正常工作(前提是您绑定了条件函数或显式地传入self
):随着这些变化,输出变成:
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