On 01/06/2015 06:25 AM, Chen CH Ji wrote:
Based on nova-specs api-microversions.rst
we support following function definition format, but it violate the
hacking rule pep8 F811 because duplicate function definition
we should use #noqa for them , but considering microversion may live for
long time ,
keep adding #noqa may be a little bit ugly, can anyone suggest a good
solution for it ? thanks
> @api_version(min_version='2.1')
> def _version_specific_func(self, req, arg1):
> pass
>
> @api_version(min_version='2.5')
> def _version_specific_func(self, req, arg1):
> pass
Hey Kevin,
This was actually one of my reservations about the proposed
microversioning implementation -- i.e. having functions that are named
exactly the same, only decorated with the microversioning notation. It
kinda reminds me of the hell of debugging C++ code that uses STL: how
does one easily know which method one is in when inside a debugger?
That said, the only other technique we could try to use would be to not
use a decorator and instead have a top-level dispatch function that
would inspect the API microversion (only when the API version makes a
difference to the output or input of that function) and then dispatch
the call to a helper method that had the version in its name.
So, for instance, let's say you are calling the controller's GET
/$tenant/os-hosts method, which happens to get routed to the
nova.api.openstack.compute.contrib.hosts.HostController.index() method.
If you wanted to modify the result of that method and the API
microversion is at 2.5, you might do something like:
def index(self, req):
req_api_ver = utils.get_max_requested_api_version(req)
if req_api_ver == (2, 5):
return self.index_2_5(req)
return self.index_2_1(req)
def index_2_5(self, req):
results = self.index_2_1(req)
# Replaces 'host' with 'host_name'
for result in results:
result['host_name'] = result['host']
del result['host']
return results
def index_2_1(self, req):
# Would be a rename of the existing index() method on
# the controller....
Another option would be to use something like JSON-patch to determine
the difference between two output schemas and automatically translate
one to another... but that would be a huge effort.
That's the only other way I can think of besides disabling F811, which I
really would not recommend, since it's a valuable safeguard against
duplicate function names (especially duplicated test methods).
Best,
-jay
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