Re: overloaded functions and NULL

Tom Lane wrote:
> Kris Jurka <books(at)ejurka(dot)com> writes:
>
>>The below code creates overloaded
>>functions that do not produce this error when called with a NULL argument.
>
>
>>jurka=# CREATE FUNCTION g(int) RETURNS int AS 'SELECT 1;' LANGUAGE sql;
>>CREATE FUNCTION
>>jurka=# CREATE FUNCTION g(float) RETURNS int AS 'SELECT 2;' LANGUAGE sql;
>>CREATE FUNCTION
>
>
> float (a/k/a float8) is the preferred type in the numeric hierarchy,
> so it will win in a tug-of-war against int. There are other cases
> where it would lose (eg, had you declared g(text)). The objective
> of the type rules is most certainly not to fail in any ambiguous
> situation --- if we did, we'd have a completely unusable system.

I have to had that in normal cases the g argument type is a known type
so all is automagically solved:

CREATE OR REPLACE FUNCTION sp_bar ( INTEGER )
RETURNS INTEGER AS'
BEGIN
RAISE NOTICE ''INTEGER'';
return 0;
END;
' LANGUAGE 'plpgsql';

CREATE OR REPLACE FUNCTION sp_bar ( FLOAT )
RETURNS INTEGER AS'
BEGIN
RAISE NOTICE ''FLOAT'';
return 0;
END;
' LANGUAGE 'plpgsql';

CREATE OR REPLACE FUNCTION sp_foo ( )
RETURNS INTEGER AS'
DECLARE
my INTEGER := 4;
BEGIN
perform sp_bar( my );
my = NULL;
perform sp_bar( my );

return 0;
END;
' LANGUAGE 'plpgsql';

# select sp_foo();
NOTICE: INTEGER
CONTEXT: PL/pgSQL function "sp_foo" line 4 at perform
NOTICE: INTEGER
CONTEXT: PL/pgSQL function "sp_foo" line 6 at perform
sp_foo
--------
0
(1 row)

AS the OP can see even calling sp_bar with a null value then
the correct function is called.

Regards
Gaetano Mendola