Re: Using substr with user defined types

darcy@druid.net (D'Arcy J.M. Cain) writes:
> I created a type (for passwords) but I can't seem to use substr.  I
> suppose that's because it is my own type because the errors suggest that
> there is no substr (actually it says ltrim) function for that type.

Yup --- the system has no idea how to apply any functions to a
user-defined type except the ones you specifically define for that type.

If you make a type-conversion function "text(yourtype) returns text"
then the system will figure out that it should apply that function
whenever you use your type as the argument of a function that needs
text.  But without such a function, the system will not assume that
it can do anything text-ish with the datatype.
        regards, tom lane