Re: [HACKERS] IS OF

Joe Conway <mail@joeconway.com> writes:
> Tom Lane wrote:
>> I'm unconvinced that the parse-time-constant implementation Lockhart
>> started has anything whatever to do with the semantics the SQL99 spec
>> has in mind.

> Yeah - I've realized this is quite a bit harder than it seemed on the
> surface. However it is still useful, as is, when working with
> polymorphic functions.

In fact you could argue that our current behavior is *more* useful than
what the spec says for polymorphics.  You would not want the special
case for NULLs, in most cases, I'd think.  NULLs have perfectly well
defined datatype.

However, it troubles me to be using a spec-defined syntax for a behavior
that is not standard.  I'd prefer to change the syntax if we are going
to keep the behavior.  That probably puts it in the "too late for 7.4"
category.  So I'm inclined to follow the path of leaving it undocumented
for now, implementing a new syntax in 7.5, and documenting it under that
syntax then.

            regards, tom lane