Allow the syntax CREATE TYPE foo, with no parameters, to permit explicit

creation of a shell type.  This allows a less hacky way of dealing with
the mutual dependency between a datatype and its I/O functions: make a
shell type, then make the functions, then define the datatype fully.
We should fix pg_dump to handle things this way, but this commit just deals
with the backend.

Martijn van Oosterhout, with some corrections by Tom Lane.

1 files changed, 27 insertions, 1 deletions

diff --git a/src/backend/utils/adt/pseudotypes.c b/src/backend/utils/adt/pseudotypes.c
index 105598afcce..98934328271 100644
--- a/src/backend/utils/adt/pseudotypes.c
+++ b/src/backend/utils/adt/pseudotypes.c
@@ -16,7 +16,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/pseudotypes.c,v 1.15 2004/12/31 22:01:22 pgsql Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/pseudotypes.c,v 1.16 2006/02/28 22:37:26 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -321,3 +321,29 @@ anyelement_out(PG_FUNCTION_ARGS)
 
 	PG_RETURN_VOID();			/* keep compiler quiet */
 }
+
+/*
+ * shell_in		- input routine for "shell" types (those not yet filled in).
+ */
+Datum
+shell_in(PG_FUNCTION_ARGS)
+{
+	ereport(ERROR,
+			(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+			 errmsg("cannot accept a value of a shell type")));
+
+	PG_RETURN_VOID();			/* keep compiler quiet */
+}
+
+/*
+ * shell_out		- output routine for "shell" types.
+ */
+Datum
+shell_out(PG_FUNCTION_ARGS)
+{
+	ereport(ERROR,
+			(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+			 errmsg("cannot display a value of a shell type")));
+
+	PG_RETURN_VOID();			/* keep compiler quiet */
+}