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+$PostgreSQL: pgsql/doc/src/sgml/plperl.sgml,v 2.33 2004/12/11 20:03:37 petere Exp $
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<chapter id="plperl">
<title>Global Values in PL/Perl</title>
<para>
- You can use the global hash <varname>%_SHARED</varname> to store
- data between function calls. For example:
+ You can use the global hash <varname>%_SHARED</varname> to store
+ data, including code references, between function calls for the
+ lifetime of the current session, which is bounded from below by
+ the lifetime of the current transaction.
+ </para>
+
+ <para>
+ Here is a simple example for shared data:
<programlisting>
CREATE OR REPLACE FUNCTION set_var(name text, val text) RETURNS text AS $$
if ($_SHARED{$_[0]} = $_[1]) {
SELECT get_var('sample');
</programlisting>
</para>
+
+ <para>
+ Here is a slightly more complicated example using a code reference:
+
+<programlisting>
+CREATE OR REPLACE FUNCTION myfuncs() RETURNS void AS $$
+ $_SHARED{myquote} = sub {
+ my $arg = shift;
+ $arg =~ s/(['\\])/\\$1/g;
+ return "'$arg'";
+ };
+$$ LANGUAGE plperl;
+
+SELECT myfuncs(); /* initializes the function */
+
+/* Set up a function that uses the quote function */
+
+CREATE OR REPLACE FUNCTION use_quote(TEXT) RETURNS text AS $$
+ my $text_to_quote = shift;
+ my $qfunc = $_SHARED{myquote};
+ return &$qfunc($text_to_quote);
+$$ LANGUAGE plperl;
+</programlisting>
+
+ (You could have replaced the above with the one-liner
+ <literal>return $_SHARED{myquote}->($_[0]);</literal>
+ at the expense of readability.)
+ </para>
</sect1>
<sect1 id="plperl-trusted">