Re: "fix" for plpgsql polymorphism - Mailing list pgsql-patches

From Bruce Momjian
Subject Re: "fix" for plpgsql polymorphism
Date
Msg-id 200307201752.h6KHqWt03180@candle.pha.pa.us
Whole thread Raw
In response to Re: "fix" for plpgsql polymorphism  (Joe Conway <mail@joeconway.com>)
List pgsql-patches
Your patch has been added to the PostgreSQL unapplied patches list at:

    http://momjian.postgresql.org/cgi-bin/pgpatches

I will try to apply it within the next 48 hours.

---------------------------------------------------------------------------


Joe Conway wrote:
> Tom Lane wrote:
> >>You can alias $0, similar to the argument variables. And, I confirmed
> >>that you cannot change the value, similar to the argument variables:
> >
> > Perhaps you shouldn't mark it isconst; then it would actually have some
> > usefulness (you could use it directly as a temporary variable to hold
> > the intended result).  I can't see much value in aliasing it if it's
> > const, either.
>
> OK; the only change in this version is "isconst = false;". Now you can
> use $0 as a result placeholder if desired. E.g.:
>
> create or replace function tmp(anyelement, anyelement) returns anyarray as '
> declare
>   v_ret alias for $0;
>   v_el1 alias for $1;
>   v_el2 alias for $2;
> begin
>   v_ret := ARRAY[v_el1, v_el2];
>   return v_ret;
> end;
> ' language 'plpgsql';
>
> create table f(f1 text, f2 text, f3 int, f4 int);
> insert into f values ('a','b',1,2);
> insert into f values ('z','x',3,4);
>
> select tmp(f1,f2) from f;
> select tmp(f3,f4) from f;
>
> Joe

> Index: src/pl/plpgsql/src/pl_comp.c
> ===================================================================
> RCS file: /opt/src/cvs/pgsql-server/src/pl/plpgsql/src/pl_comp.c,v
> retrieving revision 1.59
> diff -c -r1.59 pl_comp.c
> *** src/pl/plpgsql/src/pl_comp.c    1 Jul 2003 21:47:09 -0000    1.59
> --- src/pl/plpgsql/src/pl_comp.c    3 Jul 2003 17:59:48 -0000
> ***************
> *** 354,359 ****
> --- 354,395 ----
>                   function->fn_rettyplen = typeStruct->typlen;
>                   function->fn_rettypelem = typeStruct->typelem;
>                   perm_fmgr_info(typeStruct->typinput, &(function->fn_retinput));
> +
> +                 /*
> +                  * install $0 reference, but only for polymorphic
> +                  * return types
> +                  */
> +                 if (procStruct->prorettype == ANYARRAYOID ||
> +                     procStruct->prorettype == ANYELEMENTOID)
> +                 {
> +                     char        buf[32];
> +
> +                     /* name for variable */
> +                     snprintf(buf, sizeof(buf), "$%d", 0);
> +
> +                     /*
> +                      * Normal return values get a var node
> +                      */
> +                     var = malloc(sizeof(PLpgSQL_var));
> +                     memset(var, 0, sizeof(PLpgSQL_var));
> +
> +                     var->dtype = PLPGSQL_DTYPE_VAR;
> +                     var->refname = strdup(buf);
> +                     var->lineno = 0;
> +                     var->datatype = build_datatype(typeTup, -1);
> +                     var->isconst = false;
> +                     var->notnull = false;
> +                     var->default_val = NULL;
> +
> +                     /* preset to NULL */
> +                     var->value = 0;
> +                     var->isnull = true;
> +                     var->freeval = false;
> +
> +                     plpgsql_adddatum((PLpgSQL_datum *) var);
> +                     plpgsql_ns_additem(PLPGSQL_NSTYPE_VAR, var->varno,
> +                                        var->refname);
> +                 }
>               }
>               ReleaseSysCache(typeTup);
>

>
> ---------------------------(end of broadcast)---------------------------
> TIP 4: Don't 'kill -9' the postmaster

--
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

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