Re: How to check whether a data type can be cast to another

Kareem Sedki <isiscreation@gmail.com> writes:
> The problem I faced is that the type 'any' is not permitted in
> procedural languages. If it were permitted, then we could have a
> function like is_castable( value ANY, target_type TEXT) and then we
> would catch exceptions if they are thrown.

ANYELEMENT maybe?

> Here is what we have, there is a field in which we should store
> different data types and another field in the same row to store the
> identifier of the original data type of the first field. The first field
> should be polymorphic.

Although actually I think you should stop right here and rethink what
you are doing.  It sounds a whole lot to me like you are trying to build
an EAV store, and that seldom leads to anything good.  It is much better
to spend the necessary effort up-front to work out a concrete
fully-typed schema for your database.

            regards, tom lane