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Document pltcl's return_null command.

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This commit is contained in:
Tom Lane 2001-04-30 22:22:34 +00:00
parent 955c8771f8
commit c8b5598a11
1 changed files with 10 additions and 3 deletions
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13
doc/src/sgml/pltcl.sgml
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@ -1,5 +1,5 @@
<!--
$Header: /cvsroot/pgsql/doc/src/sgml/pltcl.sgml,v 2.8 2001/03/25 10:16:12 petere Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/pltcl.sgml,v 2.9 2001/04/30 22:22:34 tgl Exp $
-->
<chapter id="pltcl">
@ -96,8 +96,10 @@ CREATE FUNCTION <replaceable>funcname</replaceable> (<replaceable>argument-types
</programlisting>
When the function is called, the arguments are given as
variables $1 ... $n to the Tcl procedure body. For example,
a function
variables <literal>$1</literal> ... <literal>$n</literal> to the
Tcl procedure body. The result is returned
from the Tcl code in the usual way, with a <literal>return</literal>
statement. For example, a function
returning the higher of two int4 values could be defined as:
<programlisting>
@ -107,6 +109,11 @@ CREATE FUNCTION tcl_max (int4, int4) RETURNS int4 AS '
' LANGUAGE 'pltcl';
</programlisting>
To return a NULL value from a PL/Tcl function, execute
<literal>return_null</literal>.
</para>
<para>
Composite type arguments are given to the procedure as Tcl arrays.
The element names
in the array are the attribute names of the composite