E.2 Categorization of Library Units
1
[Library units can be categorized according to the
role they play in a distributed program. Certain restrictions are associated
with each category to ensure that the semantics of a distributed program
remain close to the semantics for a nondistributed program.]
2/3
{
AI05-0243-1}
A
categorization pragma is a library unit pragma (see
10.1.5)
that
specifies a corresponding categorization
aspect. A categorization aspect restricts the declarations,
child units, or semantic dependences of the library unit to which it
applies. A
categorized library unit is a library unit
that
has a categorization aspect that is True to
which a categorization pragma applies.
3/3
{
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The pragmas Shared_Passive, Remote_Types, and Remote_Call_Interface are
categorization pragmas
, and the associated aspects
are categorization aspects. In addition, for the purposes of this
Annex, the
aspect Pure (see 10.2.1)
is considered a categorization aspect and the pragma Pure
(see
10.2.1) is considered a categorization
pragma.
4/3
{
8652/0078}
{
AI95-00048-01}
{
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[
A library package or generic library package is
called a
shared passive library unit if
the a
Shared_Passive
aspect of the unit is True pragma
applies to it.
A library package or generic
library package is called a
remote types library unit if
the a
Remote_Types
aspect of the unit is True pragma
applies to it.
A library
unit package
or generic library package is called a
remote call interface
if
the a Remote_Call_Interface
aspect of the unit is True pragma
applies to it.]
A
normal library unit
is one
for to
which no categorization
aspect is True pragma
applies.
4.a/3
Proof: {
AI05-0243-1}
These terms (other than “normal library unit”)
are really defined in the following clauses.
4.a.1/1
Ramification: {
8652/0078}
{
AI95-00048-01}
A library subprogram can be a remote call interface,
but it cannot be a remote types or shared passive library unit.
5/3
{
AI05-0206-1}
{
AI05-0243-1}
[The various categories of library units and the associated restrictions
are described in this clause and its subclauses. The categories are related
hierarchically in that the library units of one category can depend semantically
only on library units of that category or an earlier one, except that
the body of a remote types or remote call interface library unit is unrestricted
,
the declaration of a remote types or remote call interface library unit
may depend on preelaborated normal library units that are mentioned only
in private with clauses, and all categories can depend on limited views.
6/3
{
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The overall hierarchy (including declared pure) is as follows
(with a lower-numbered category being earlier in the sense of the previous
paragraph):
6.1/3
1.
Declared Pure
6.2/3
2.
Shared Passive
6.3/3
3.
Remote Types
6.4/3
4.
Remote Call Interface
6.5/3
5.
Normal (no restrictions)
Paragraphs
7 through 11 were deleted.
7/3
Can depend only on other declared pure library
units;
8/3
Can depend only on other shared passive or declared
pure library units;
9/3
The declaration of the library unit can depend
only on other remote types library units, or one of the above library
unit categories, or limited views, or preelaborated normal library units
that are mentioned only in private with clauses; the body of the library
unit is unrestricted;
10/3
The declaration of the library unit can depend
only on other remote call interfaces, or one of the above; the body of
the library unit is unrestricted;
11/3
Unrestricted.
12
Declared pure and shared passive library units are
preelaborated. The declaration of a remote types or remote call interface
library unit is required to be preelaborable. ]
Implementation Requirements
13/1
This paragraph was
deleted.{
8652/0079}
{
AI95-00208-01}
For a given library-level type declared in a preelaborated
library unit or in the declaration of a remote types or remote call interface
library unit, the implementation shall choose the same representation
for the type upon each elaboration of the type's declaration for different
partitions of the same program.
Implementation Permissions
14
Implementations are allowed to define other categorization
pragmas.
Wording Changes from Ada 95
14.a/2
{
8652/0078}
{
AI95-00048-01}
Corrigendum: Clarified that a library subprogram
can be a remote call interface unit.14.b/2
{
8652/0079}
{
AI95-00208-01}
Corrigendum: Removed the requirement that
types be represented the same in all partitions, because it prevents
the definition of heterogeneous distributed systems and goes much further
than required. Wording Changes from Ada 2005
14.c/3
{
AI05-0206-1}
We now allow private withs of preelaborated units
in Remote Types and Remote Call Interface units; this is documented as
an extension in the sections where this is defined normatively.14.d/3
{
AI05-0243-1}
We have introduced categorization aspects; these
are documented as extensions in the clauses where they actually are defined.
Ada 2005 and 2012 Editions sponsored in part by Ada-Europe
