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A subprogram_renaming_declaration can serve as the completion of a
subprogram_declaration; such a renaming_declaration is called a
renaming-as-body. A subprogram_renaming_declaration that is not a
completion is called a renaming-as-declaration, and is used to rename a
subprogram (possibly an enumeration literal) or an entry.
Syntax
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subprogram_renaming_declaration ::=
subprogram_specification renames callable_entity_name;
Name Resolution Rules
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The expected profile for the callable_entity_name is the profile given
in the subprogram_specification.
Legality Rules
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The profile of a renaming-as-declaration shall be mode-conformant with
that of the renamed callable entity.
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The profile of a renaming-as-body shall be subtype-conformant with that
of the renamed callable entity, and shall conform fully to that of the
declaration it completes. If the renaming-as-body completes that
declaration before the subprogram it declares is frozen, the subprogram
it declares takes its convention from the renamed subprogram; otherwise
the convention of the renamed subprogram shall not be Intrinsic.
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A name that denotes a formal parameter of the subprogram_specification
is not allowed within the callable_entity_name.
Static Semantics
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A renaming-as-declaration declares a new view of the renamed entity. The
profile of this new view takes its subtypes, parameter modes, and
calling convention from the original profile of the callable entity,
while taking the formal parameter names and default_expressions from the
profile given in the subprogram_renaming_declaration. The new view is a
function or procedure, never an entry.
Dynamic Semantics
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For a call on a renaming of a dispatching subprogram that is overridden,
if the overriding occurred before the renaming, then the body executed
is that of the overriding declaration, even if the overriding
declaration is not visible at the place of the renaming; otherwise, the
inherited or predefined subprogram is called.
NOTES
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(11) A procedure can only be renamed as a procedure. A function whose
defining_designator is either an identifier or an operator_symbol can be
renamed with either an identifier or an operator_symbol; for renaming as
an operator, the subprogram specification given in the
renaming_declaration is subject to the rules given in See section 6.6 Overloading of Operators, for
operator declarations. Enumeration literals can be renamed as functions;
similarly, attribute_references that denote functions (such as
references to Succ and Pred) can be renamed as functions. An entry can
only be renamed as a procedure; the new name is only allowed to appear
in contexts that allow a procedure name. An entry of a family can be
renamed, but an entry family cannot be renamed as a whole.
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(12) The operators of the root numeric types cannot be renamed because
the types in the profile are anonymous, so the corresponding
specifications cannot be written; the same holds for certain attributes,
such as Pos.
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(13) Calls with the new name of a renamed entry are
procedure_call_statements and are not allowed at places where the syntax
requires an entry_call_statement in conditional_ and timed_entry_calls,
nor in an asynchronous_select; similarly, the Count attribute is not
available for the new name.
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(14) The primitiveness of a renaming-as-declaration is determined by its
profile, and by where it occurs, as for any declaration of (a view of) a
subprogram; primitiveness is not determined by the renamed view. In
order to perform a dispatching call, the subprogram name has to denote a
primitive subprogram, not a non-primitive renaming of a primitive
subprogram.
Examples
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Examples of subprogram renaming declarations:
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procedure My_Write(C : in Character) renames Pool(K).Write;
-- See section 4.1.3 Selected Components
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function Real_Plus(Left, Right : Real ) return Real renames "+";
function Int_Plus (Left, Right : Integer) return Integer renames "+";
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function Rouge return Color renames Red; -- See section 3.5.1 Enumeration Types
function Rot return Color renames Red;
function Rosso return Color renames Rouge;
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function Next(X : Color) return Color renames Color'Succ;
-- See section 3.5.1 Enumeration Types
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Example of a subprogram renaming declaration with new parameter names:
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function "*" (X,Y : Vector) return Real renames Dot_Product;
-- See section 6.1 Subprogram Declarations
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Example of a subprogram renaming declaration with a new default expression:
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function Minimum(L : Link := Head) return Cell renames Min_Cell;
-- See section 6.1 Subprogram Declarations