!standard 13.12                                      04-02-05   AI95-00372/01
!class amendment 03-12-30
!status No Action (10-0-0) 04-03-05
!status work item 03-12-30
!status received 03-12-30
!priority Medium
!difficulty Medium
!subject Restrictions for default stream attributes of elementary types

!summary

The following restrictions identifier 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

We introduce an additional restriction identifier that forbids the use
of default stream attributes for elementary types.

The following restriction identifier is added:

    No_Default_Elementary_Stream_Attributes

!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.

!wording

The following restrictions identifier is language-defined:

    No_Default_Elementary_Stream_Attributes

There are no use of default stream attributes for elementary types.

!example


!ACATS test

B-Tests should be constructed to verify that this restriction is
enforced.

!appendix

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