Re: Permissions for CREATE OPERATOR CLASS

Alvaro Herrera <alvherre(at)atentus(dot)com> writes:
> I was playing around and got this:

> alvh=> create type my_cash (input = cash_in, output = cash_out, internallength = variable);
> ERROR: TypeCreate: function cash_out(opaque) does not exist

Yeah, the CREATE TYPE code is now much stricter about the allowed
signatures of the I/O functions. The input function for a type foo
must be one of
foo_in(cstring) returns foo
foo_in(opaque) returns foo
foo_in(cstring) returns opaque
foo_in(opaque) returns opaque
while the output must be one of
foo_out(foo) returns cstring
foo_out(opaque) returns cstring
foo_out(foo) returns opaque
foo_out(opaque) returns opaque
so unless you use "opaque" you cannot use the same I/O function for
two different types. (Possibly the error message should complain about
foo_out(foo) not foo_out(opaque).)

If we hear a lot of squawks about that, we can discuss how to weaken
the rules ... but IMHO the entire point here is to introduce some type
safety into the use of I/O functions ...

regards, tom lane