Re: RfD: more powerful "any" types

On Sep 9, 2009, at 6:39 AM, Tom Lane wrote:

> 1. Is a completely unconstrained argument type (ie "any") of any real
> use to PL functions, and if so how can we expose that usefulness?
> The only clear thing to do with such an argument is IS NULL/IS NOT  
> NULL
> tests, which might or might not be worth the trouble.

If you can pass an "any" to pg_typeof(), it's possible for functions  
to determine the types of arguments themselves and then to decide what  
to do with them (cast, etc.). I can see no reason not to give this  
ability to function authors, can you?

> 2. Is there any use for arguments with type constraints not covered
> by the existing ANYFOO rules, and if so what do we add for that?
>
> One comment on point 2 is that it was foreseen from the beginning
> that there would be need for ANYELEMENT2 etc, and I'm actually rather
> surprised that we've gone this long without adding them.  Alvaro made
> a good point about not wanting to multiply the various hard-wired
> OID references, but perhaps some judicious code refactoring could
> prevent a notational disaster.

The difference between allowing ANYELEMENT2, ANYELEMENT3, ANYELEMENT .  
++$i and allowing "any" escapes me.

Best,

David