On 25/08/07, Robert Brewer <[EMAIL PROTECTED]> wrote:
>
>
>
> Hi all,
>
> I just found another corner case in the WSGI spec
> that I thought I'd share so you all can check your
> WSGI components for similar problems. Basically,
> it comes down to error handling. Here's a simple
> example:
>
>
> class Middleware(object):
>
> def __init__(self, nextapp, environ, start_response):
> try:
> self.response = nextapp(environ, start_response)
> self.iter_response = iter(self.response)
> return
> except SomeException:
> self.close()
>
> def close(self):
> if hasattr(self.response, "close"):
> self.response.close()
>
> def __iter__(self):
> return self
>
> def next(self):
> try:
> return self.iter_response.next()
> except AnotherException:
> self.close()
> raise StopIteration
A question related to this example. In what ways is using
__iter__/yield better or worse than defining next() in terms of
performance, compatibility with different Python versions etc. For
example:
class Generator:
def __init__(self, generator, callback, environ):
self.__generator = generator
self.__callback = callback
self.__environ = environ
def __iter__(self):
for item in self.__generator:
yield item
def close(self):
if hasattr(self.__generator, 'close'):
self.__generator.close()
self.__callback(self.__environ)
class ExecuteOnCompletion:
def __init__(self, application, callback):
self.__application = application
self.__callback = callback
def __call__(self, environ, start_response):
try:
result = self.__application(environ, start_response)
except:
self.__callback(self.__environ)
raise
return Generator(result, self.__callback, environ)
Just curious.
Graham
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