Re: [HACKERS] Initial review of xslt with no limits patch

[David E. Wheeler]

On Aug 6, 2010, at 1:49 PM, Pavel Stehule wrote:

> yes it is one a possibility and probably best. The nice of this
> variant can be two forms like current variadic does -  foo(.., a :=
> 10, b := 10) or foo(.., variadic ARRAY[(a,10),(b,10)])

I started fiddling and got as far as this:


CREATE TYPE pair AS ( key text, val text );

CREATE OR REPLACE FUNCTION pair(anyelement, anyelement) RETURNS pair
LANGUAGE SQL AS $$
    SELECT ROW($1, $2)::pair;
$$;

CREATE OR REPLACE FUNCTION pair(text, text) RETURNS pair
LANGUAGE SQL AS $$
    SELECT ROW($1, $2)::pair;
$$;

CREATE OPERATOR ~> (
        LEFTARG = anyelement,
        RIGHTARG = anyelement,
        PROCEDURE = pair
);

CREATE OPERATOR ~> (
        LEFTARG = text,
        RIGHTARG = text,
        PROCEDURE = pair
);

CREATE OR REPLACE FUNCTION foo(variadic pair[]) RETURNS SETOF text
LANGUAGE SQL AS $$
--    SELECT unnest($1)::text
    SELECT $1[1].key
    UNION  SELECT $1[1].val
    UNION  SELECT $1[2].key
    UNION  SELECT $1[2].val;
$$;

SELECT foo('this' ~> 'that', 1 ~> 4);

Not bad, I think. I kind of like it. It reminds me how much I hate the % hstore 
construction operator, though (the new name for =>).

Best,

David



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