Обсуждение: inherits clause for CREATE TYPE? -

Pavel Stehule <pavel.stehule@gmail.com> writes:
> My idea is implement inherits clause for CREATE TYPE command.

-1.  We have enough problems dealing with alterations of inherited
rowtypes already.  As long as inheritance is restricted to tables,
we can use table locking to help prevent problems --- but there's
no provision for locking free-standing types.  And introducing
locking on types would cost way more than this seems likely to be
worth.

            regards, tom lane

On Wed, Dec 18, 2019 at 12:38 PM Pavel Stehule <pavel.stehule@gmail.com> wrote:
>
> Hi
>
> I had a talk with one boy about development in plpgsql. He uses table's functions. More times he uses returns types
basedon some table type + few attributes. Now he use a ugly hack - he create a view on table plus some columns - and
thenhe use the view related type as table function result type. For similar uses cases there can be interesting to have
apossibility to create types by extending other types. Probably almost all functionality is inside now - so it should
notbe hard work. 
>
> My idea is implement inherits clause for CREATE TYPE command.
>
> Some like
>
> CREATE TYPE fx_rt (xx int) INHERITS(pg_class);
>
> What do you think about this idea?

How about using composition style approaches?

create type base as (...)

create type extended as  (b base, ...)

create function foo() returns extended as ...

merlin