Re: Function with record type as argument

On Feb 22, 2005, at 11:03 AM, Tom Lane wrote:

> Sean Davis <sdavis2(at)mail(dot)nih(dot)gov> writes:
>> Thanks for the reply. Just for fun, I did create the function in
>> pl/perlu without difficulty. However, I can't call it, as record
>> types
>> do not seem to match any prototyping....
>
> I don't think plperl has a validator function, so it's not going to
> complain at CREATE FUNCTION time, but it definitely barfs at runtime:
>
> /* Disallow pseudotype argument */
> if (typeStruct->typtype == 'p')
> {
> free(prodesc->proname);
> free(prodesc);
> ereport(ERROR,
> (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
> errmsg("plperl functions cannot take type
> %s",
>
> format_type_be(procStruct->proargtypes[i]))));
> }
>
> The point about what input will be considered to match type-wise is
> another good one that I hadn't thought about. Looking at the source
> code, it appears that 8.0 will consider an explicit ROW(...) construct
> to match a RECORD argument, but not a named composite type (e.g.,
> a row coming from a table) :-(. This is probably an oversight stemming
> from the fact that no one's ever exercised the case.
>
> I don't have plperl installed on this machine, but pltcl behaves about
> the same:
>
> regression=# create function f1(record) returns int as $$return 1$$
> language pltcl;
> CREATE FUNCTION
> regression=# select f1(row(33,44));
> ERROR: pltcl functions cannot take type record
> regression=# select f1(i.*) from int8_tbl i;
> ERROR: function f1(int8_tbl) does not exist
>
> The first select is actually a "success", since control is getting as
> far as letting pltcl decide it won't do it.
>
> plpgsql probably isn't ever going to allow RECORD arguments, since it
> likes to work with known types, but in principle I think the other PLs
> could handle the case. They all are willing to take named composite
> types and this doesn't seem much different for their purposes.

Tom,

As usual, thanks for the enlightenment. Allowing generic record types
seems quite intuitive to a perl programmer and since perl is a very
"untyped" language, it seems quite practicable to allow? Of course, I
don't have the knowledge to "make it so".... It does seem that for
some applications, allowing pls other than pgsql to get access to
whatever is passed (a generic record type) would be a useful extension.

Sean