Re: Range Types, constructors, and the type system

On Tue, Jul 5, 2011 at 11:11 AM, Jeff Davis <pgsql@j-davis.com> wrote:
> On Tue, 2011-07-05 at 10:06 -0400, Robert Haas wrote:
>> > But if it's actually better, we should do it. If an intermediate type
>> > seems to be problematic, or if people think it's strange to require
>> > casting, then I think this is reasonable.
>>
>> I don't understand how the bespoke syntax avoids the need for a cast?
>
> It doesn't, it just avoids the need for an intermediate type.
>
> What I meant was that it might be strange to require a cast on the
> result of a function call, because we don't really do that anywhere
> else. Florian pointed out that it's common to require casting the
> ARRAY[] constructor, so that has more of a precedent. I'm not really
> sure how much that matters.
>
> I'm OK with the intermediate type, but Florian seems skeptical of that
> idea.

How about the idea of creating a family of four constructor functions
for each new range type?  The functions would be named after the range
type, with "_cc", "_co", "_oc", and "_oo" appended.  So, then, instead
of writing:

RANGE(1,8,'c','o')::int8range

...or somesuch, you could just say:

int8range_co(1,8)

...which is both more compact and less ugly, IMHO, and seems to
circumvent all the type system problems as well.

-- 
Robert Haas
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