1
[A subprogram_body specifies the execution of a subprogram.]
2/2
{20218AI95−00218−03} subprogram_body::=
[overriding_indicator]
subprogram_specification is
declarative_part
begin
handled_sequence_of_statements
end [designator];
3
If a designator appears at the end of a subprogram_body, it shall repeat the defining_designator of the subprogram_specification.
4
[In contrast to other bodies,] a subprogram_body need not be the completion of a previous declaration[, in which case the body declares the subprogram]. If the body is a completion, it shall be the completion of a subprogram_declaration or generic_subprogram_declaration. The profile of a subprogram_body that completes a declaration shall conform fully to that of the declaration. {full conformance (required)}
5
A subprogram_body is considered a declaration. It can either complete a previous declaration, or itself be the initial declaration of the subprogram.
6
{elaboration (non−generic subprogram_body) [partial]} The elaboration of a non−generic subprogram_body has no other effect than to establish that the subprogram can from then on be called without failing the Elaboration_Check.
6.a
Ramification: See 12.2 for elaboration of a generic body. Note that protected subprogram_bodies never get elaborated; the elaboration of the containing protected_body allows them to be called without failing the Elaboration_Check.
7
{execution (subprogram_body) [partial]} [The execution of a subprogram_body is invoked by a subprogram call.] For this execution the declarative_part is elaborated, and the handled_sequence_of_statements is then executed.
8
Example of procedure body:
9
procedure Push(E : in Element_Type; S : in out Stack) is begin if S.Index = S.Size then raise Stack_Overflow; else S.Index := S.Index + 1; S.Space(S.Index) := E; end if; end Push;
10
Example of a function body:
11
function Dot_Product(Left, Right : Vector) return Real is Sum : Real := 0.0; begin Check(Left'First = Right'First and Left'Last = Right'Last); for J in Left'Range loop Sum := Sum + Left(J)*Right(J); end loop; return Sum; end Dot_Product;
11.a
{extensions to Ada 83} A renaming_declaration may be used instead of a subprogram_body.
11.b
The syntax rule for subprogram_body now uses the syntactic category handled_sequence_of_statements.
11.c
The declarative_part of a subprogram_body is now required; that doesn't make any real difference, because a declarative_part can be empty.
11.d
We have incorporated some rules from RM83−6.5 here.
11.e
RM83 forgot to restrict the definition of elaboration of a subprogram_body to non−generics.
11.f/2
{20218AI95−00218−03} Overriding_indicator is added to subprogram_body.