E.2.2 Remote Types Library Units
A remote types library unit supports the definition
of types intended for use in communication between active partitions.
Syntax
The
form of a
pragma
Remote_Types is as follows:
pragma Remote_Types[(
library_unit_name)];
Legality Rules
A
remote types library unit is a library unit to which the pragma
Remote_Types applies. The following restrictions apply to the declaration
of such a library unit:
it shall be preelaborable;
it shall depend semantically only on declared pure,
shared passive, or other remote types library units;
it shall not contain the declaration of any variable
within the visible part of the library unit;
the full view of each type declared in the visible
part of the library unit that has any available stream attributes shall
support external streaming (see
13.13.2).
An
access type declared in the visible part of a remote types or remote
call interface library unit is called a
remote access type.
Such
a type shall be:
an access-to-subprogram type, or
a general access type that designates a class-wide
limited private type or a class-wide private type extension all of whose
ancestors are either private type extensions or limited private types.
A type that is derived from a remote access type
is also a remote access type.
The following restrictions
apply to the use of a remote access-to-subprogram type:
A value of a remote access-to-subprogram type shall
be converted only to or from another (subtype-conformant) remote access-to-subprogram
type;
The
prefix
of an Access
attribute_reference
that yields a value of a remote access-to-subprogram type shall statically
denote a (subtype-conformant) remote subprogram.
The following restrictions
apply to the use of a remote access-to-class-wide type:
The primitive subprograms of the corresponding
specific limited private type shall only have access parameters if they
are controlling formal parameters; each non-controlling formal parameter
shall support external streaming (see
13.13.2);
A value of a remote access-to-class-wide type shall
be explicitly converted only to another remote access-to-class-wide type;
A value of a remote access-to-class-wide type shall
be dereferenced (or implicitly converted to an anonymous access type)
only as part of a dispatching call where the value designates a controlling
operand of the call (see
E.4, “
Remote
Subprogram Calls”).
The Storage_Pool attribute is not defined for a
remote access-to-class-wide type; the expected type for an
allocator
shall not be a remote access-to-class-wide type. A remote access-to-class-wide
type shall not be an actual parameter for a generic formal access type.
The Storage_Size attribute of a remote access-to-class-wide type yields
0; it is not allowed in an
attribute_definition_clause.
5 A remote types library unit need not
be pure, and the types it defines may include levels of indirection implemented
by using access types. User-specified Read and Write attributes (see
13.13.2) provide for sending values of
such a type between active partitions, with Write marshalling the representation,
and Read unmarshalling any levels of indirection.
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