Issue 4661: Python mapping issue: value boxes                                                                                                                                                                       (python-ftf)
Source: AT&T (Dr. Duncan Grisby, )
Nature: Uncategorized Issue
Severity: 
Summary: I suggest a change to the mapping for value boxes, that makes them
much more convenient to use. I believe that none of the Python ORBs
implement the currently specified mapping, so changing the mapping at
this point will not affect any ORB implementations or application
code.

I suggest that the new mapping is:

------
  Value boxes are mapped to the normal mapping of the boxed type, or
  None for null value boxes. For example, given IDL

    valuetype BoxedString string;
    interface I {
      void example(in BoxedString a, in BoxedString b);
    };

  the operation could be called as:

    obj.example("Hello", None)

------

Discussion: this mapping has one limitation, in that in a boxed object
reference type it is impossible to distinguish a null value box from a
non-null value box containing a nil object reference. This is
considered acceptable since the IDL to Java mapping has the same
property; there is a clear precedent for this kind of mapping.

Resolution: Accept the proposed changes
Revised Text: In section 3.10, replace the paragraph starting "Value boxes are mapped" with: 
Value boxes are mapped to the normal mapping of the boxed type, or None for null value boxes. For example, given IDL 

    valuetype BoxedString string;
    interface I {
      void example(in BoxedString a, in BoxedString b);
    };
the operation could be called as: 
    obj.example("Hello", None) 

Actions taken:
November 5, 2001: received issue
October 23, 2002: closed issue
Discussion: 
Discussion: this mapping has one limitation, in that in a boxed object reference type it is impossible to distinguish a null value box from a non-null value box containing a nil object reference. This is considered acceptable since the IDL to Java mapping has the same property; there is a clear precedent for this kind of mapping.
End of Annotations:=====
To: issues@omg.org
Subject: Python mapping issue: value boxes
From: Duncan Grisby <dgrisby@uk.research.att.com>
Date: Mon, 05 Nov 2001 12:44:57 +0000
Sender: dpg1@uk.research.att.com
Content-Type: text
X-UIDL: d<C!!_4l!!`7/e9B)pd9

I suggest a change to the mapping for value boxes, that makes them
much more convenient to use. I believe that none of the Python ORBs
implement the currently specified mapping, so changing the mapping at
this point will not affect any ORB implementations or application
code.

I suggest that the new mapping is:

------
  Value boxes are mapped to the normal mapping of the boxed type, or
  None for null value boxes. For example, given IDL

    valuetype BoxedString string;
    interface I {
      void example(in BoxedString a, in BoxedString b);
    };

  the operation could be called as:

    obj.example("Hello", None)

------

Discussion: this mapping has one limitation, in that in a boxed object
reference type it is impossible to distinguish a null value box from a
non-null value box containing a nil object reference. This is
considered acceptable since the IDL to Java mapping has the same
property; there is a clear precedent for this kind of mapping.

Cheers,

Duncan.

-- 
 -- Duncan Grisby  \  Research Engineer  --
  -- AT&T Laboratories Cambridge          --
   -- http://www.uk.research.att.com/~dpg1 --