Re: [Libvir] Python bindings, errors & exceptions

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.

> 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.