Version 1.1 of ai05s/ai05-0161-1.txt

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!standard H.4(23)          09-07-08 AI05-0161-1/01
!class Amendment 09-07-08
!status work item 09-07-08
!status received 09-06-14
!priority Medium
!difficulty Medium
!subject Restrictions for default stream attributes of elementary types
!summary
The following restrictions identifiers exist:
No_Default_Elementary_Stream_Attributes
!problem
For elementary types, the representation in terms of stream elements is implementation defined. The only way to ensure interoperability of streams between different implementations is by having user-defined stream attributes for all data exchanged. However, it is easy to inadvertantly use a stream operation for a type that has no user-defined stream attributes, or for a composite type with such a subcomponent.
The proposed restriction would make sure that no default implementation of stream attributes for elementary types is used.
!proposal
(See wording.)
!wording
Add after H.4(23):
No_Default_Elementary_Stream_Attributes
There is no use of default stream attributes for elementary types.
!discussion
We cannot forbid all default stream attributes, since the default attributes for composite types are defined to compose from their elements, which does not raise an issue. However, if a composite type has a subcomponent of an elementary type for which their is no user-defined stream attribute, it would be considered a "use" of the default elementary type stream attribute, and therefore forbidden.
!example
--!corrigendum H.4(23)
!ACATS test
B-Tests should be constructed to verify that this restriction is enforced.
!appendix

Editor's note:

The original proposal for this restriction did not suggest where it would be
added to the Standard. I rather arbitraryly picked H.4(23).

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