[Libvir] Python bindings, errors & exceptions
Richard W.M. Jones
rjones at redhat.com
Fri Mar 23 14:12:28 UTC 2007
Daniel Veillard wrote:
> On Fri, Mar 23, 2007 at 01:28:36PM +0000, Richard W.M. Jones wrote:
>> Daniel P. Berrange wrote:
>>> Actually looks like it is the generated code actually. The generator.py
>>> appears to only add in the 'raise libvirtError' stuff if the return value
>>> is a virConnectPtr/virDomainPtr/virNeworkPtr object - any other function
>>> with a non-object return value gives back None upon error.
>> The generator.py code as it stands doesn't deal with the case where a
>> function is prototyped (in C) as returning 'int'.
>>
>> If I were to modify generator.py so that it adds the check for functions
>> returning int, then it doesn't work because there is not enough
>> information from just the C return type to tell what the Python return
>> type will be.
>
> Right and that's why the automatic generator does not raise exception
> automatically. For example getMaxMem could return -1 to mean unlimited
> (e.g. on Domain 0) which is a correct return code in my opinion and
> should not be considered and error, while getMem returning -1 should
> really mean an error occured.
> No way automatic code could catch the subtle difference.
getMaxMem definitely sounds like a problem. I wouldn't have spotted
that on my own.
>> We could do some run-time type magic in the generated wrapper, although
>> that seems evil.
>
> At best keep a list of functions where one would not want to generate
> exception automatically.
Yes, I'm working on this.
Thanks,
Rich.
--
Emerging Technologies, Red Hat http://et.redhat.com/~rjones/
64 Baker Street, London, W1U 7DF Mobile: +44 7866 314 421
"[Negative numbers] darken the very whole doctrines of the equations
and make dark of the things which are in their nature excessively
obvious and simple" (Francis Maseres FRS, mathematician, 1759)
-------------- next part --------------
A non-text attachment was scrubbed...
Name: smime.p7s
Type: application/x-pkcs7-signature
Size: 3237 bytes
Desc: S/MIME Cryptographic Signature
URL: <http://listman.redhat.com/archives/libvir-list/attachments/20070323/090b3a8f/attachment-0001.bin>
More information about the libvir-list
mailing list