[英]re-using the variable in a function in a class in python
我将尝试用一小段代码来解释我面临的问题:
class MyHandler(PatternMatchingEventHandler):
patterns = ["*.csv","*.processing", "*.transforming","*.loading"]
def process(self, event):
eventFileName = event.src_path
eventType = event.event_type
if eventType == 'moved':
eventFileName = event.dest_path
fileNameWithPath, fileExtension = os.path.splitext(eventFileName)
if fileExtension == '.processing':
# Here some function is called to do something, and then appends ".loading" to the file name
testVariable = 75.3
if fileExtension == '.loading':
print testVariable
def on_moved(self, event):
self.process(event)
def on_created(self, event):
self.process(event)
if __name__ == '__main__':
observer = Observer()
observer.schedule(MyHandler(), path='.')
observer.start()
try:
while True:
time.sleep(1)
except KeyboardInterrupt:
observer.stop()
observer.join()
当我尝试执行上述操作时,出现此错误: global name 'testVariable' is not defined
哪种含义有意义,但是如何进行以上工作? 我尝试全局定义“ testVariable”并初始化为0,并尝试使用上面代码中显示的方式使用它,但效果不佳。 我也尝试在类内部将testVariable初始化为testVariable=0
( testVariable=0
在“ patterns = .....”行之后,但是我遇到了这个错误: local variable "testVariable" referenced before assignment
指向print testVariable
local variable "testVariable" referenced before assignment
。 。
“(...)我如何进行上述工作?”
通过在条件语句之外定义testVariable
。 例如:
def process(self, event):
eventFileName = event.src_path
testVariable = 0
...
这将使其在process
功能中可用。 如果希望在整个课程中都可以使用它,可以在这里定义它:
class MyHandler(PatternMatchingEventHandler):
patterns = ["*.csv","*.processing", "*.transforming","*.loading"]
testVariable = 0
但是然后您必须通过以下函数中的self
对象访问它:
def process(self, event):
...
if fileExtension == '.processing':
# Here some function is called to do something, and then appends ".loading" to the file name
self.testVariable = 75.3
仅当扩展名为“ .processing”时,testVariable才存在。 如果它是“ .loading”,程序将尝试打印一个尚未存在的变量。
如果语句未在Python中创建垃圾回收范围,那么您不必在外部“声明”它,只要在if-tree中的某个位置,tesVariable即可获取值。
def process(self, event):
def extension():
eventFileName = event.src_path
eventType = event.event_type
if eventType == 'moved':
eventFileName = event.dest_path
return os.path.splitext(eventFileName)[1]
if extension() == '.processing':
...
if extension() == '.loading':
...
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