Re: BUG #2490: '||' and type casting for user defined types

[Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>]

"Nikolay Samokhvalov" <pg-bugs(at)samokhvalov(dot)com> writes:
> CREATE CAST (aaa AS text) WITHOUT FUNCTION
> 	AS IMPLICIT;
> CREATE CAST (text AS aaa) WITHOUT FUNCTION
> 	AS IMPLICIT;

> trash=# select ('as' || 'df')::aaa;
>  aaa  
> ------
>  asdf
> (1 row)

> In the last case, function aaa_in() wasn't invoked at all and we obtained 
> the sting of type aaa with length > 3...

Well, sure.  You declared the text to aaa cast as WITHOUT FUNCTION; that
says the system can relabel any legal text value as an aaa.  If you want
to enforce a length limit on the cast result, you need to write a cast
function that does it.

			regards, tom lane