Implement a psql command "\ef" to edit the definition of a function.

In support of that, create a backend function pg_get_functiondef().
The psql command is functional but maybe a bit rough around the edges...

Abhijit Menon-Sen

Author: tglsfdc

doc/src/sgml/func.sgml

@@ -1,4 +1,4 @@
-<!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.443 2008/07/21 04:47:00 tgl Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.444 2008/09/06 00:01:21 tgl Exp $ -->
 
  <chapter id="functions">
   <title>Functions and Operators</title>
@@ -11562,6 +11562,10 @@ SELECT pg_type_is_visible('myschema.widget'::regtype);
     <primary>pg_get_ruledef</primary>
    </indexterm>
 
+   <indexterm>
+    <primary>pg_get_functiondef</primary>
+   </indexterm>
+
    <indexterm>
     <primary>pg_get_function_arguments</primary>
    </indexterm>
@@ -11643,6 +11647,11 @@ SELECT pg_type_is_visible('myschema.widget'::regtype);
        <entry>decompile internal form of an expression, assuming that any Vars
        in it refer to the relation indicated by the second parameter</entry>
       </row>
+      <row>
+       <entry><literal><function>pg_get_functiondef</function>(<parameter>func_oid</parameter>)</literal></entry>
+       <entry><type>text</type></entry>
+       <entry>get definition of a function</entry>
+      </row>
       <row>
        <entry><literal><function>pg_get_function_arguments</function>(<parameter>func_oid</parameter>)</literal></entry>
        <entry><type>text</type></entry>
@@ -11756,6 +11765,8 @@ SELECT pg_type_is_visible('myschema.widget'::regtype);
   </para>
 
   <para>
+   <function>pg_get_functiondef</> returns a complete
+   <command>CREATE OR REPLACE FUNCTION</> statement for a function.
    <function>pg_get_function_arguments</function> returns the argument list
    of a function, in the form it would need to appear in within
    <command>CREATE FUNCTION</>.

doc/src/sgml/ref/psql-ref.sgml

@@ -1,5 +1,5 @@
 <!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/psql-ref.sgml,v 1.209 2008/07/03 03:37:16 tgl Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/psql-ref.sgml,v 1.210 2008/09/06 00:01:21 tgl Exp $
 PostgreSQL documentation
 -->
 
@@ -1195,6 +1195,29 @@ testdb=&gt;
       </varlistentry>
 
 
+      <varlistentry>
+        <term><literal>\ef <replaceable class="parameter">function_description</replaceable> </literal></term>
+
+        <listitem>
+        <para>
+         This command fetches and edits the definition of the named function,
+         in the form of a <command>CREATE OR REPLACE FUNCTION</> command.
+         Editing is done in the same way as for <literal>\e</>.
+         After the editor exits, the updated command waits in the query buffer;
+         type semicolon or <literal>\g</> to send it, or <literal>\r</>
+         to cancel.
+        </para>
+
+        <para>
+         The target function can be specified by name alone, or by name
+         and arguments, for example <literal>foo(integer, text)</>.
+         The argument types must be given if there is more
+         than one function of the same name.
+        </para>
+        </listitem>
+      </varlistentry>
+
+
       <varlistentry>
         <term><literal>\echo <replaceable class="parameter">text</replaceable> [ ... ]</literal></term>
         <listitem>