Re: row->ARRAY or row->table casting?

Tom Lane ha scritto:
> Nico Sabbi <nsabbi@officinedigitali.it> writes:
>
>> is there any way to cast a generic row to an array or to a table type?
>>
>
> "row(...)::composite_type" should work in 8.2 and up.
>
>             regards, tom lane
>
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I'm using 8.2.4.

What's the right syntax for a case like this?

nb1=# select r.a from (select row(tab1.*)::tab1 as r from tab1)x;
ERROR:  missing FROM-clause entry for table "r"
LINE 1: select r.a from (select row(tab1.*)::tab1 as r from tab1)x;
               ^

I tried many variations (including casting x as tab1) obtaining only
syntax errors.

Thanks,
    Nico