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<H1> 6.3 Subprogram Bodies</H1>
<DIV Class="Paranum"><FONT SIZE=-2>1</FONT></DIV>
<DIV Class="Normal"> [A <FONT FACE="Arial, Helvetica">subprogram_body</FONT>
specifies the execution of a subprogram.] </DIV>
<H4 ALIGN=CENTER>Syntax</H4>
<DIV Class="Paranum"><FONT SIZE=-2>2</FONT></DIV>
<DIV Class="SyntaxIndented"><FONT FACE="Arial, Helvetica">subprogram_body<A NAME="I3076"></A>
::= </FONT><BR>
<A NAME="I3077"></A><FONT FACE="Arial, Helvetica">subprogram_specification</FONT> <B>is</B><BR>
<A NAME="I3078"></A><FONT FACE="Arial, Helvetica">declarative_part</FONT><BR>
<B>begin</B><BR>
<A NAME="I3079"></A><FONT FACE="Arial, Helvetica">handled_sequence_of_statements</FONT><BR>
<B>end</B> [<A NAME="I3080"></A><FONT FACE="Arial, Helvetica">designator</FONT>];</DIV>
<DIV Class="Paranum"><FONT SIZE=-2>3</FONT></DIV>
<DIV Class="SyntaxIndented">If a <FONT FACE="Arial, Helvetica">designator</FONT>
appears at the end of a <FONT FACE="Arial, Helvetica">subprogram_body</FONT>,
it shall repeat the <FONT FACE="Arial, Helvetica">defining_designator</FONT>
of the <FONT FACE="Arial, Helvetica">subprogram_specification</FONT>.
</DIV>
<H4 ALIGN=CENTER>Legality Rules</H4>
<DIV Class="Paranum"><FONT SIZE=-2>4</FONT></DIV>
<DIV Class="Normal"> [In contrast to other bodies,] a <FONT FACE="Arial, Helvetica">subprogram_body</FONT>
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 <FONT FACE="Arial, Helvetica">subprogram_declaration</FONT>
or <FONT FACE="Arial, Helvetica">generic_subprogram_declaration</FONT>.
The profile of a <FONT FACE="Arial, Helvetica">subprogram_body</FONT>
that completes a declaration shall conform fully to that of the declaration.
<A NAME="I3081"></A></DIV>
<H4 ALIGN=CENTER>Static Semantics</H4>
<DIV Class="Paranum"><FONT SIZE=-2>5</FONT></DIV>
<DIV Class="Normal"> A <FONT FACE="Arial, Helvetica">subprogram_body</FONT>
is considered a declaration. It can either complete a previous declaration,
or itself be the initial declaration of the subprogram. </DIV>
<H4 ALIGN=CENTER>Dynamic Semantics</H4>
<DIV Class="Paranum"><FONT SIZE=-2>6</FONT></DIV>
<DIV Class="Normal"> <A NAME="I3082"></A>The elaboration of a non-generic
<FONT FACE="Arial, Helvetica">subprogram_body</FONT> has no other effect
than to establish that the subprogram can from then on be called without
failing the Elaboration_Check. </DIV>
<DIV Class="Paranum"><FONT SIZE=-2>6.a</FONT></DIV>
<DIV Class="Annotations"><FONT SIZE=-1><B>Ramification: </B>See <A HREF="AA-12-2.html">12.2</A>
for elaboration of a generic body. Note that protected <FONT FACE="Arial, Helvetica">subprogram_bodies</FONT>
never get elaborated; the elaboration of the containing <FONT FACE="Arial, Helvetica">protected_body</FONT>
allows them to be called without failing the Elaboration_Check. </FONT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>7</FONT></DIV>
<DIV Class="Normal"> <A NAME="I3083"></A>[The execution of a <FONT FACE="Arial, Helvetica">subprogram_body</FONT>
is invoked by a subprogram call.] For this execution the <FONT FACE="Arial, Helvetica">declarative_part</FONT>
is elaborated, and the <FONT FACE="Arial, Helvetica">handled_sequence_of_statements</FONT>
is then executed. </DIV>
<H4 ALIGN=CENTER>Examples</H4>
<DIV Class="Paranum"><FONT SIZE=-2>8</FONT></DIV>
<DIV Class="Normal" Style="margin-bottom: 0.4em"> <I>Example of procedure
body:</I> </DIV>
<DIV Class="Paranum"><FONT SIZE=-2>9</FONT></DIV>
<DIV Class="Examples"><TT><B>procedure</B> Push(E : <B>in</B> Element_Type; S : <B>in</B> <B>out</B> Stack) <B>is</B><BR>
<B>begin</B><BR>
<B>if</B> S.Index = S.Size <B>then</B><BR>
<B>raise</B> Stack_Overflow;<BR>
<B>else</B><BR>
S.Index := S.Index + 1;<BR>
S.Space(S.Index) := E;<BR>
<B>end</B> <B>if</B>;<BR>
<B>end</B> Push;</TT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>10</FONT></DIV>
<DIV Class="Wide" Style="margin-bottom: 0.4em"> <I>Example of a function
body:</I> </DIV>
<DIV Class="Paranum"><FONT SIZE=-2>11</FONT></DIV>
<DIV Class="Examples"><TT><B>function</B> Dot_Product(Left, Right : Vector) <B>return</B> Real <B>is</B><BR>
Sum : Real := 0.0;<BR>
<B>begin</B><BR>
Check(Left'First = Right'First <B>and</B> Left'Last = Right'Last);<BR>
<B>for</B> J <B>in</B> Left'Range <B>loop</B><BR>
Sum := Sum + Left(J)*Right(J);<BR>
<B>end</B> <B>loop</B>;<BR>
<B>return</B> Sum;<BR>
<B>end</B> Dot_Product;</TT></DIV>
<H4 ALIGN=CENTER>Extensions to Ada 83</H4>
<DIV Class="Paranum"><FONT SIZE=-2>11.a</FONT></DIV>
<DIV Class="Annotations"><FONT SIZE=-1><A NAME="I3084"></A>A <FONT FACE="Arial, Helvetica">renaming_declaration</FONT>
may be used instead of a <FONT FACE="Arial, Helvetica">subprogram_body</FONT>.
</FONT></DIV>
<H4 ALIGN=CENTER>Wording Changes from Ada 83</H4>
<DIV Class="Paranum"><FONT SIZE=-2>11.b</FONT></DIV>
<DIV Class="Annotations"><FONT SIZE=-1>The syntax rule for <FONT FACE="Arial, Helvetica">subprogram_body</FONT>
now uses the syntactic category <FONT FACE="Arial, Helvetica">handled_sequence_of_statements</FONT>.</FONT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>11.c</FONT></DIV>
<DIV Class="Annotations"><FONT SIZE=-1>The <FONT FACE="Arial, Helvetica">declarative_part</FONT>
of a <FONT FACE="Arial, Helvetica">subprogram_body</FONT> is now required;
that doesn't make any real difference, because a <FONT FACE="Arial, Helvetica">declarative_part</FONT>
can be empty.</FONT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>11.d</FONT></DIV>
<DIV Class="Annotations"><FONT SIZE=-1>We have incorporated some rules
from RM83-6.5 here.</FONT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>11.e</FONT></DIV>
<DIV Class="Annotations"><FONT SIZE=-1>RM83 forgot to restrict the definition
of elaboration of a <FONT FACE="Arial, Helvetica">subprogram_body</FONT>
to non-generics. </FONT></DIV>
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