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<H1> 5.6 Block Statements</H1>
<DIV Class="Paranum"><FONT SIZE=-2>1</FONT></DIV>
<DIV Class="Normal"> [A <FONT FACE="Arial, Helvetica">block_statement</FONT>
encloses a <FONT FACE="Arial, Helvetica">handled_sequence_of_statements</FONT>
optionally preceded by a <FONT FACE="Arial, Helvetica">declarative_part</FONT>.]
</DIV>
<H4 ALIGN=CENTER>Syntax</H4>
<DIV Class="Paranum"><FONT SIZE=-2>2</FONT></DIV>
<DIV Class="SyntaxIndented"><FONT FACE="Arial, Helvetica">block_statement<A NAME="I2983"></A>
::= </FONT><BR>
[<I>block_</I><A NAME="I2984"></A><FONT FACE="Arial, Helvetica">statement_identifier</FONT>:]<BR>
[<B>declare</B><BR>
<A NAME="I2985"></A><FONT FACE="Arial, Helvetica">declarative_part</FONT>]<BR>
<B>begin</B><BR>
<A NAME="I2986"></A><FONT FACE="Arial, Helvetica">handled_sequence_of_statements</FONT><BR>
<B>end</B> [<I>block_</I><A NAME="I2987"></A><FONT FACE="Arial, Helvetica">identifier</FONT>];</DIV>
<DIV Class="Paranum"><FONT SIZE=-2>3</FONT></DIV>
<DIV Class="SyntaxIndented">If a <FONT FACE="Arial, Helvetica">block_statement</FONT>
has a <I>block_</I><FONT FACE="Arial, Helvetica">statement_identifier</FONT>,
then the <FONT FACE="Arial, Helvetica">identifier</FONT> shall be repeated
after the <B>end</B>; otherwise, there shall not be an <FONT FACE="Arial, Helvetica">identifier</FONT>
after the <B>end</B>. </DIV>
<H4 ALIGN=CENTER>Static Semantics</H4>
<DIV Class="Paranum"><FONT SIZE=-2>4</FONT></DIV>
<DIV Class="Normal"> A <FONT FACE="Arial, Helvetica">block_statement</FONT>
that has no explicit <FONT FACE="Arial, Helvetica">declarative_part</FONT>
has an implicit empty <FONT FACE="Arial, Helvetica">declarative_part</FONT>.
</DIV>
<DIV Class="Paranum"><FONT SIZE=-2>4.a</FONT></DIV>
<DIV Class="Annotations"><FONT SIZE=-1><B>Ramification: </B>Thus, other
rules can always refer to the <FONT FACE="Arial, Helvetica">declarative_part</FONT>
of a <FONT FACE="Arial, Helvetica">block_statement</FONT>. </FONT></DIV>
<H4 ALIGN=CENTER>Dynamic Semantics</H4>
<DIV Class="Paranum"><FONT SIZE=-2>5</FONT></DIV>
<DIV Class="Normal"> <A NAME="I2988"></A>The execution of a <FONT FACE="Arial, Helvetica">block_statement</FONT>
consists of the elaboration of its <FONT FACE="Arial, Helvetica">declarative_part</FONT>
followed by the execution of its <FONT FACE="Arial, Helvetica">handled_sequence_of_statements</FONT>.
</DIV>
<H4 ALIGN=CENTER>Examples</H4>
<DIV Class="Paranum"><FONT SIZE=-2>6</FONT></DIV>
<DIV Class="Normal" Style="margin-bottom: 0.4em"> <I>Example of a
block statement with a local variable:</I> </DIV>
<DIV Class="Paranum"><FONT SIZE=-2>7</FONT></DIV>
<DIV Class="Examples"><TT>Swap:<BR>
<B>declare</B><BR>
Temp : Integer;<BR>
<B>begin</B><BR>
Temp := V; V := U; U := Temp;<BR>
<B>end</B> Swap;</TT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>7.a</FONT></DIV>
<DIV Class="Annotations"><FONT SIZE=-1><B>Ramification: </B>If task objects
are declared within a <FONT FACE="Arial, Helvetica">block_statement</FONT>
whose execution is completed, the <FONT FACE="Arial, Helvetica">block_statement</FONT>
is not left until all its dependent tasks are terminated (see <A HREF="AA-7-6.html">7.6</A>).
This rule applies to completion caused by a transfer of control.</FONT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>7.b</FONT></DIV>
<DIV Class="Annotations"><FONT SIZE=-1>Within a <FONT FACE="Arial, Helvetica">block_statement</FONT>,
the block name can be used in expanded names denoting local entities
such as Swap.Temp in the above example (see <A HREF="AA-4-1-3.html">4.1.3</A>).
</FONT></DIV>
<H4 ALIGN=CENTER>Wording Changes from Ada 83</H4>
<DIV Class="Paranum"><FONT SIZE=-2>7.c</FONT></DIV>
<DIV Class="Annotations"><FONT SIZE=-1>The syntax rule for <FONT FACE="Arial, Helvetica">block_statement</FONT>
now uses the syntactic category <FONT FACE="Arial, Helvetica">handled_sequence_of_statements</FONT>.
</FONT></DIV>
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