[omniORB] Return Struct o None

[Michael]

Hi Antonio,

there is no conecpt of None/Nil/Null whatever when return a
struct/string/int or any datatype. That is because you're dealing with
pods and not pointers/references. This becomes more apparent when you're
imagening the following construct in C++:

int x = myinft->get_whatever();
So when your servant returned None, what should this do in this code?

You can only return None when returning an object reference (because it
is.. a reference :) - that will map to a nil reference in other
languages). So for what you want to accomplish it might be best to
return a sequence and make that empty in case there is no return value,
so in your IDL:

typedef sequence<SInfo> SInfoSeq;

SInfoSeq get_personal_info(in wstring name);

in python:
   def get_personal_info(self, name):
       if name in self.personal_dict:
          return [SInfo(self.personal_dict[name]['id'],
                       self.personal_dict[name]['address'],
                       self.personal_dict[name]['tlf'])]
       else:
          return []

As an alternative, if that interface should usually return something (so
a miss is an exceptional event) you could throw a user exception instead
(never throw CORBA::OBJECT_NOT_EXIST in such a case, because it tells
the orb that the object reference you called get_personal_info on does
not exist - in case of location forwards and other scenarios that will
lead to disaster). Bottomline, in this case alter your idl:

exception PersonalInfoNotFoundException {
  string message;
};

SInfo get_personal_info(in wstring name) raises
(PersonalInfoNotFoundException);

And in python:
...
else:
  raise PersonalInfoNotFoundExceptino("Nothing there")

br
michael


Antonio Beamud Montero wrote:
> Hi all:
> I've defined a struct, and a method that returns this struct type. The
> problem is when I try to return a null value instead this struct. For
> example:
> 
> idl:
> ...
> struct SInfo {
>     wstring id;
>     wstring address;
>     wstring tlf;
> }
> 
> SInfo get_personal_info(in wstring name);
> 
> in python:
> ..
>   def get_personal_info(self, name):
>       if name in self.personal_dict:
>          return SInfo(self.personal_dict[name]['id'],
>                       self.personal_dict[name]['address'],
>                       self.personal_dict[name]['tlf'])
>       else:
>          return None
> 
> If the name exists, all works well, but if not exists, the next error
> appears:
> omniORB.CORBA.BAD_PARAM:
> ORBA.BAD_PARAM(omniORB.BAD_PARAM_WrongPythonType, CORBA.COMPLETED_MAYBE)
> 
> I've tried with None, Corba.types.NoneType and CORBA.Object._nil
>        , but the same error.
> 
> Thanks.
> 
> 
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