Re: Making cstring type less pseudo and more real

En Thu, 22 Aug 2002 11:52:08 -0400
Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> escribió:

> The original problem with "opaque" is gone in CVS tip:
>
> regression=# select cash_out(2);
> ERROR: Function cash_out(integer) does not exist
> Unable to identify a function that satisfies the given argument types
> You may need to add explicit typecasts

Yes, but how does it work?

alvh=> CREATE TABLE money_test (a money);
CREATE TABLE
alvh=> INSERT INTO money_test VALUES (2);
ERROR: column "a" is of type 'money' but expression is of type 'integer'
You will need to rewrite or cast the expression
alvh=> INSERT INTO money_test VALUES ('2');
ERROR: Bad money external representation 2
alvh=> INSERT INTO money_test VALUES ('2.00');
ERROR: Bad money external representation 2.00
alvh=> INSERT INTO money_test VALUES ('$2.00');
ERROR: Bad money external representation $2.00
alvh=> INSERT INTO money_test VALUES ('2'::money);
ERROR: Bad money external representation 2
alvh=> INSERT INTO money_test VALUES (money(2));
ERROR: Function money(integer) does not exist
Unable to identify a function that satisfies the given argument types
You may need to add explicit typecasts

> I am thinking about declaring type cstring in pg_type as
> pass-by-reference with typlen set to -2, and altering the places that
> interpret typlen to understand -2 as meaning null-terminated string.
> (Currently, typlen > 0 means a fixed-length type, typlen = -1 is used
> for varlena values which have a length word, and there's no meaning
> assigned to other negative typlen values.)

Sounds good.

> I haven't really looked to see how many places would need to change,
> but if it's not too many then this seems reasonable to do --- it would
> make the cstring feature a lot more robust than it is now.

At least all places that call get_typlenbyval() and get_typlen() or get
the typlen directly, it seems. They are not too much, AFAICS...

--
Alvaro Herrera (<alvherre[a]atentus.com>)
Si no sabes adonde vas, es muy probable que acabes en otra parte.