Re: proposal sql: labeled function params

Hello

2008/8/15 Hannu Krosing <hannu@2ndquadrant.com>:
> On Fri, 2008-08-15 at 10:01 -0400, Tom Lane wrote:
>> Peter Eisentraut <peter_e@gmx.net> writes:
>> > Random googling shows me that Oracle appears to use a syntax like
>> >     name => value
>> > This is actually a feature that I would like to see implemented soonish, so if
>> > anyone has input on the possible syntax consequences, please comment.
>>
>> We've been over this territory before.  The problem with "name => value"
>> is that it requires reserving a perfectly good user-defined operator name.
>
> We could declare, that using operator => in function argument expression
> requires parenthesis : func( a => (b => c) means param a with value
> expression (b => c) nad just func((b => c)) means first param with value
> (b=>c)
>

or just use := operator?

select new_person(name := 'Smith') - it's simple and consistent with pl/pgsql.

> the main use of named params is calling functions with default values,
> and giving some params. there I'm more concerned about default args and
> rules for finding right function in presence of functions with both
> multiple args and default values for some.
>
> create function f(a int) ...
>
> create function f(a int, b int default 7)
>
> create function f(text text)
>
> and then calling f(4) - which one would it call
>
> what about f('4')
>
> Of course, we could also have default values without named params, and
> just require keyword DEFAULT where we want default value :)
>
>> "value AS name", on the other hand, accomplishes the same in a more
>> SQL-looking fashion with no new reserved word (since AS is already
>> fully reserved).
>
> would it be more natural / SQL-like to use "value AS name" or "name AS
> value" ?
>

it's question, because SQL wit AS clause don't specify value, it
specifies label.

Regards
Pavel


> -------------
> Hannu
>
>
>