Add optional "validator" function to languages that can validate the

function body (and other properties) as a function in the language
is created.  This generalizes ad hoc code that already existed for
the built-in languages.

The validation now happens after the pg_proc tuple of the new function
is created, so it is possible to define recursive SQL functions.

Add some regression test cases that cover bogus function definition
attempts.

2 files changed, 33 insertions, 5 deletions

diff --git a/doc/src/sgml/ref/create_language.sgml b/doc/src/sgml/ref/create_language.sgml
index e5f47be9ffe..42d7c9b4877 100644
--- a/doc/src/sgml/ref/create_language.sgml
+++ b/doc/src/sgml/ref/create_language.sgml
@@ -1,5 +1,5 @@
 <!--
-$Header: /cvsroot/pgsql/doc/src/sgml/ref/create_language.sgml,v 1.23 2002/05/18 15:44:47 petere Exp $
+$Header: /cvsroot/pgsql/doc/src/sgml/ref/create_language.sgml,v 1.24 2002/05/22 17:20:58 petere Exp $
 PostgreSQL documentation
 -->
 
@@ -17,7 +17,7 @@ PostgreSQL documentation
  <refsynopsisdiv>
 <synopsis>
 CREATE [ TRUSTED ] [ PROCEDURAL ] LANGUAGE <replaceable class="parameter">langname</replaceable>
-    HANDLER <replaceable class="parameter">call_handler</replaceable>
+    HANDLER <replaceable class="parameter">call_handler</replaceable> [ VALIDATOR <replaceable>valfunction</replaceable> ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -113,6 +113,32 @@ CREATE [ TRUSTED ] [ PROCEDURAL ] LANGUAGE <replaceable class="parameter">langna
       </para>
      </listitem>
     </varlistentry>
+
+    <varlistentry>
+     <term><literal>VALIDATOR</literal> <replaceable class="parameter">valfunction</replaceable></term>
+
+     <listitem>
+      <para>
+       <replaceable class="parameter">valfunction</replaceable> is the
+       name of a previously registered function that will be called
+       when a new function in the language is created, to validate the
+       new function.  The validator function must take one argument of
+       type <type>oid</type>, which will be the OID of the
+       to-be-created function, and can have any return type.  If no
+       validator function is specified, then a new function will not
+       be checked when it is created.
+      </para>
+
+      <para>
+       A validator function would typically inspect the function body
+       for syntactical correctness, but it can also look at other
+       properties of the function, for example if the language cannot
+       handle certain argument types.  To signal an error, the
+       validator function should use the <function>elog()</function>
+       function.  The return value of the function is ignored.
+      </para>
+     </listitem>
+    </varlistentry>
    </variablelist>
  </refsect1>
 
diff --git a/doc/src/sgml/release.sgml b/doc/src/sgml/release.sgml
index b25b7ef5e38..0bdb095804c 100644
--- a/doc/src/sgml/release.sgml
+++ b/doc/src/sgml/release.sgml
@@ -1,5 +1,5 @@
 <!--
-$Header: /cvsroot/pgsql/doc/src/sgml/release.sgml,v 1.137 2002/05/18 13:47:59 petere Exp $
+$Header: /cvsroot/pgsql/doc/src/sgml/release.sgml,v 1.138 2002/05/22 17:20:58 petere Exp $
 -->
 
 <appendix id="release">
@@ -24,6 +24,8 @@ CDATA means the content is "SGML-free", so you can write without
 worries about funny characters.
 -->
 <literallayout><![CDATA[
+Recursive SQL functions can be defined
+User-defined procedural languages can register a validator function to check new functions as they are created
 Functions can be executed with the privileges of the owner
 Syntax of CREATE FUNCTION has been extended to resemble SQL99
 Effects of SET within a transaction block now roll back if transaction aborts
@@ -72,7 +74,7 @@ Database and user-specific session defaults for run-time configuration variables
     <title>Changes</title>
 
     <para>
-     <programlisting>
+<literallayout>
 Ensure that sequence counters do not go backwards after a crash (Tom)
 Fix pgaccess kanji-coversion key binding (Tatsuo)
 Optimizer improvements (Tom)
@@ -90,7 +92,7 @@ contrib/tsearch dictionary improvements, see README.tsearch for
   an additional installation step (Thomas T. Thai, Teodor Sigaev)
 Fix for array subscripts handling (Tom)
 Allow EXECUTE of "CREATE TABLE AS ... SELECT" in PL/PgSQL (Tom)
-     </programlisting>
+</literallayout>
     </para>
    </sect2>
   </sect1>