Hi,
Constants are just convenience: instead of constants, user defined
functions can be used. This already works, however it's a bit verbose:
CREATE FUNCTION STATE_ACTIVE() RETURNS VARCHAR AS
$$ BEGIN RETURN 'active'; END; $$ LANGUAGE PLPGSQL;
Usage is almost the same:
SELECT * FROM USERS WHERE STATE=STATE_ACTIVE();
> therefore arbitrary macro expansion like in those "plenty of languages"
> does not seem like a good idea to me.
This is _not_ macro expansion as in C '#define'. Constants are typed,
as in C++ 'const' and Java 'static final'. The question is only:
should the user explicitly state the data type, or should the data
type be deduced from the value. Both is possible:
CREATE CONSTANT STATE_ACTIVE VALUE 'active';
CREATE CONSTANT STATE_ACTIVE TEXT VALUE 'active';
Regards,
Thomas
