8.5 Renaming Declarations
1
[A renaming_declaration
declares another name for an entity, such as an object, exception, package,
subprogram, entry, or generic unit. Alternatively, a subprogram_renaming_declaration
can be the completion of a previous subprogram_declaration.]
1.a.1/2
Glossary entry: {Renaming}
A renaming_declaration is a declaration that
does not define a new entity, but instead defines a view of an existing
entity.
Syntax
2
renaming_declaration ::=
object_renaming_declaration
|
exception_renaming_declaration
|
package_renaming_declaration
|
subprogram_renaming_declaration
|
generic_renaming_declaration
Dynamic Semantics
3
{elaboration (renaming_declaration)
[partial]} The elaboration of a
renaming_declaration
evaluates the
name that follows the reserved
word
renames and thereby determines the view and entity denoted
by this name
{renamed view}
{renamed entity}
(the
renamed view and
renamed entity).
[A
name that denotes the
renaming_declaration
denotes (a new view of) the renamed entity.]
4
9 Renaming may be used to resolve name
conflicts and to act as a shorthand. Renaming with a different identifier
or operator_symbol does not hide the old name;
the new name and the old name
need not be visible at the same places.
5
10 A task or protected object that is declared
by an explicit object_declaration can be renamed
as an object. However, a single task or protected object cannot be renamed
since the corresponding type is anonymous (meaning it has no nameable
subtypes). For similar reasons, an object of an anonymous array or access
type cannot be renamed.
6
11 A subtype
defined without any additional constraint can be used to achieve the
effect of renaming another subtype (including a task or protected subtype)
as in
7
subtype Mode is Ada.Text_IO.File_Mode;
Wording Changes from Ada 83
7.a
The second sentence of RM83-8.5(3), “At
any point where a renaming declaration is visible, the identifier, or
operator symbol of this declaration denotes the renamed entity.”
is incorrect. It doesn't say directly visible. Also, such an identifier
might resolve to something else.
7.b
The verbiage about renamings being legal “only
if exactly one...”, which appears in RM83-8.5(4) (for objects)
and RM83-8.5(7) (for subprograms) is removed, because it follows from
the normal rules about overload resolution. For language lawyers, these
facts are obvious; for programmers, they are irrelevant, since failing
these tests is highly unlikely.
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