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<H1> 12.7 Formal Packages</H1>
<DIV Class="Paranum"><FONT SIZE=-2>1</FONT></DIV>
<DIV Class="Normal"> <A NAME="I4094"></A><A NAME="I4095"></A>Formal
packages can be used to pass packages to a generic unit. The <FONT FACE="Arial, Helvetica">formal_package_declaration</FONT>
declares that the formal package is an instance of a given generic package.
Upon instantiation, the actual package has to be an instance of that
generic package. </DIV>
<H4 ALIGN=CENTER>Syntax</H4>
<DIV Class="Paranum"><FONT SIZE=-2>2</FONT></DIV>
<DIV Class="SyntaxIndented"><FONT FACE="Arial, Helvetica">formal_package_declaration<A NAME="I4096"></A>
::= </FONT><BR>
<B>with</B> <B>package</B> <A NAME="I4097"></A><FONT FACE="Arial, Helvetica">defining_identifier</FONT> <B>is</B> <B>new</B> <I>generic_package_</I><A NAME="I4098"></A><FONT FACE="Arial, Helvetica">name</FONT> <A NAME="I4099"></A><FONT FACE="Arial, Helvetica">formal_package_actual_part</FONT>;</DIV>
<DIV Class="Paranum"><FONT SIZE=-2>3</FONT></DIV>
<DIV Class="SyntaxIndented"><FONT FACE="Arial, Helvetica">formal_package_actual_part<A NAME="I4100"></A>
::= </FONT><BR>
(<>) | [<A NAME="I4101"></A><FONT FACE="Arial, Helvetica">generic_actual_part</FONT>]</DIV>
<H4 ALIGN=CENTER>Legality Rules</H4>
<DIV Class="Paranum"><FONT SIZE=-2>4</FONT></DIV>
<DIV Class="Normal"> <A NAME="I4102"></A>The <I>generic_package_</I><FONT FACE="Arial, Helvetica">name</FONT>
shall denote a generic package (the <I>template</I> for the formal package);
the formal package is an instance of the template.</DIV>
<DIV Class="Paranum"><FONT SIZE=-2>5</FONT></DIV>
<DIV Class="Normal" Style="margin-bottom: 0.4em"> The actual shall
be an instance of the template. If the <FONT FACE="Arial, Helvetica">formal_package_actual_part</FONT>
is (<>), then the actual may be any instance of the template; otherwise,
each actual parameter of the actual instance shall match the corresponding
actual parameter of the formal package (whether the actual parameter
is given explicitly or by default), as follows: </DIV>
<DIV Class="Paranum"><FONT SIZE=-2>6</FONT></DIV>
<UL Class="Bulleted"><LI TYPE=DISC>For a formal object of mode <B>in</B> the actuals match
if they are static expressions with the same value, or if they statically
denote the same constant, or if they are both the literal <B>null</B>.
</LI></UL>
<DIV Class="Paranum"><FONT SIZE=-2>7</FONT></DIV>
<UL Class="Bulleted"><LI TYPE=DISC>For a formal subtype, the actuals match if they denote
statically matching subtypes. <A NAME="I4103"></A></LI></UL>
<DIV Class="Paranum"><FONT SIZE=-2>8</FONT></DIV>
<UL Class="Bulleted"><LI TYPE=DISC>For other kinds of formals, the actuals match if they statically
denote the same entity. </LI></UL>
<DIV Class="Paranum"><FONT SIZE=-2>8.1/1</FONT></DIV>
<DIV Class="Normal"> For the purposes of matching, any actual parameter
that is the name of a formal object of mode <B>in</B> is replaced by
the formal object's actual expression (recursively). </DIV>
<H4 ALIGN=CENTER>Static Semantics</H4>
<DIV Class="Paranum"><FONT SIZE=-2>9</FONT></DIV>
<DIV Class="Normal"> A <FONT FACE="Arial, Helvetica">formal_package_declaration</FONT>
declares a generic formal package.</DIV>
<DIV Class="Paranum"><FONT SIZE=-2>10</FONT></DIV>
<DIV Class="Normal"> <A NAME="I4104"></A>The visible part of a formal
package includes the first list of <FONT FACE="Arial, Helvetica">basic_declarative_item</FONT>s
of the <FONT FACE="Arial, Helvetica">package_specification</FONT>. In
addition, if the <FONT FACE="Arial, Helvetica">formal_package_actual_part</FONT>
is (<>), it also includes the <FONT FACE="Arial, Helvetica">generic_formal_part</FONT>
of the template for the formal package. </DIV>
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