Re: Variadic parameters vs parameter defaults

"Brendan Jurd" <direvus@gmail.com> writes:
> On Wed, Dec 17, 2008 at 11:07 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> ISTM one could make a pretty good argument that this last case should
>> succeed, producing an empty-array argument.  If you buy that, then it
>> is sensible to forbid defaults for variadics,

> Yep, +1 for this approach.  I would intuitively expect that, if I omit
> variadic argument(s) when calling a function, that the function ends
> up getting an empty array of the appropriate type.

Actually, I just realized that there's another fly in the ointment:
the current variadic code allows "variadic anyarray", which is
equivalent to an appropriate number of anyelement arguments.  If we
allow defaulting then there's a big problem: no principled way to
decide what type the empty array is.

The explicit-default solution would work around that, by making the
user say what type he wants.  However it puts us right back into the
situation of having a default for a polymorphic argument, which I
was hoping to avoid.
        regards, tom lane