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6.3 Subprogram Bodies
1
A subprogram_body
specifies the execution of a subprogram.
Syntax
2
subprogram_body
::=
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.
Legality Rules
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.
Static Semantics
5
A subprogram_body
is considered a declaration. It can either complete a previous declaration,
or itself be the initial declaration of the subprogram.
Dynamic Semantics
6
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.
7
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.
Examples
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;
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