Re: [Orbit-python-list] How to use IDL unions with orbit-python?

[Jochen V. <jv...@we...>]

Hello,

thank you for the quick fix.

On Mon, Jan 28, 2002 at 09:02:01PM +0100, Johan Dahlin wrote:
> m=E5n 2002-01-28 klockan 20.07 skrev Jochen Voss:
> > Part of the problem may be the bug, which is
> > described at
> >=20
> >     http://bugs.debian.org/123848
> >=20
> > The access to union members does not follow
> > the CORBA python language mapping specification.
> > This really should be fixed.
> >=20
> Could you try the attached patch and see if it works better for you?

Yes, I tried it and it is a big improvement.
The _d and _u attributes have the correct names, now.

But there are still problems left.
I will use the following IDL file to explain.

    module TestUnion {
      interface Frosch {
	enum E2 { A, B };
	union MyUnion switch (E2) {
	case A:
	  long x;
	case B:=20
	  string s;
	};

	attribute MyUnion U;
      };
    };

Now, Section 1.3.5 of the CORBA python language mapping
says:

    Union types are mapped to classes with two attributes.
    [ ... _d and _v are explained ... ]
    For each branch, there is an additional attribute,
    which can only be accessed if the branch has been set.

This additional attribute seems to be no implemented:

    voss@tatonka [~/src/python/test-union] python
    Python 2.1.2 (#1, Jan 18 2002, 18:05:45)=20
    [GCC 2.95.4  (Debian prerelease)] on linux2
    Type "copyright", "credits" or "license" for more information.
    >>> import CORBA, TestUnion
    >>> x=3DTestUnion.Frosch.MyUnion(TestUnion.Frosch.B,"Hallo")
    >>> x
    <__main__.MyUnion instance at 0x80a606c>
    >>> x._d
    1
    >>> x._v
    'Hallo'
    >>> x.s=20
    Traceback (most recent call last):
      File "<stdin>", line 1, in ?
    AttributeError: MyUnion instance has no attribute 's'

The way I read section 1.3.5, x.s should have been 'hallo'.
Next: the specification continues:

    [...]
    * If the discriminant is not listed [in a case label],
      and there is no default, the value is "None".

This does not work, too:

    voss@tatonka [~/src/python/test-union] python
    Python 2.1.2 (#1, Jan 18 2002, 18:05:45)=20
    [GCC 2.95.4  (Debian prerelease)] on linux2
    Type "copyright", "credits" or "license" for more information.
    >>> import CORBA, TestUnion
    >>> x=3DTestUnion.Frosch.MyUnion()
    >>> x._d=3D2
    AttributeError: MyUnion instance has no attribute '_v'
    >>> x._v
    Traceback (most recent call last):
      File "<stdin>", line 1, in ?
    AttributeError: MyUnion instance has no attribute '_v'

Even if it is simply not inplemented, the first error
message looks strange.

I hope this helps,
Jochen
--=20
                                         Omm
                                      (0)-(0)
http://www.mathematik.uni-kl.de/~wwwstoch/voss/privat.html