[Orbit-python-list] Spec non-compliance re unions

[Chip R. <ch...@ni...>]

Tack requested that I send details about comments I made on IRC, so here they
are.

Copying the union example in the spec (v1.0, dated February 2001), section
1.3.5, I created this IDL:

   module Onion
   {
     interface OnionIF
     {
       union MyUnion switch (long)
       {
       case 1:   string  s;
       default:  long    x;
       };
     };
   };

To test it, I copied the Python code in the same section of the spec, giving
this:

   #! /usr/bin/env python

   import CORBA
   from   Onion import OnionIF

   u = OnionIF.MyUnion (17, 42)
   print u.x
   u = OnionIF.MyUnion (s = 'string')
   print u._d, u._v

(As an aside, I know of no way with o-p to code simply "MyUnion", because
"OnionIF" is not a valid import source.  Is this just not possible, or am I
missing something?  I probably wouldn't code it that way anyway, but was
just curious.)

When run, using o-p 0.3.0, that returns this error message:

   Traceback (innermost last):
     File "./onion-clnt", line 7, in ?
       print u.x
   AttributeError: x

Commenting out the first "print" and running again gives this:

   Traceback (innermost last):
     File "./onion-clnt", line 8, in ?
       u = OnionIF.MyUnion (s = 'string')
   TypeError: this function takes no keyword arguments

What actually works is this code:

   #! /usr/bin/env python

   import CORBA
   from   Onion import OnionIF

   u = OnionIF.MyUnion (17, 42)
   print u.v
   u = OnionIF.MyUnion (1, 'string')
   print u.d, u.v

Which prints this:

   42
   1 string

Which is the form I'm currently using in my application.  Earlier, I had found
a similar situation related to structures, which I'll describe in a subsequent
message.

-- 
Chip