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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
A
categorization pragma is a library unit pragma (see
10.1.5)
that restricts the declarations, child units, or semantic dependences
of the library unit to which it applies. A
categorized library unit
is a library unit to which a categorization pragma applies.
3
The pragmas Shared_Passive, Remote_Types, and
Remote_Call_Interface are categorization pragmas. In addition, for the
purposes of this Annex, the pragma Pure (see
10.2.1)
is considered a categorization pragma.
4/1
A library package or generic
library package is called a
shared passive library unit if a Shared_Passive
pragma applies to it.
A library package or generic
library package is called a
remote types library unit if a Remote_Types
pragma applies to it.
A library unit is called a
remote call interface if a Remote_Call_Interface pragma applies
to it.
A
normal library unit is one to which
no categorization pragma applies.
5
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.
6
The overall hierarchy
(including declared pure) is as follows:
7
- Declared Pure
-
Can depend only on other declared pure library units;
8
- Shared Passive
-
Can depend only on other shared passive or declared pure library units;
9
- Remote Types
-
The declaration of the library unit can depend only on other remote types
library units, or one of the above; the body of the library unit is unrestricted;
10
- Remote Call Interface
-
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
- Normal
-
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.
Implementation Permissions
14
Implementations are allowed to define other categorization
pragmas.
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