relacl parsing method?

Hi,

I want to find out whether a user has a select privilege on a particular
database. This is what I see when it does:

# select relacl from pg_class where relname = 'mydbtable';
                                  relacl
--------------------------------------------------------------------------
 {mydbname=arwdxt/mydbname,mydbuser=r/mydbname}
(1 row)

Is this the best way to parse that easily from within PostgreSQL:

# select 1 from pg_class where relname = 'mydbtable' and relacl ~ 'mydbuser=r/mydbname';
 ?column?
----------
        1
(1 row)

# select 1 from pg_class where relname = 'mydbtable' and relacl ~ 'mydbuser=w/mydbname';
 ?column?
----------
(0 rows)

Where is this documented? I tried searching for 'relacl' and 'aclitem' in
the docs, but didn't come up with much.

I did find a Perl module at http://search.cpan.org/~dwheeler/Pg-Priv-0.10/
that seems to extract relacl and parse it on its own, which sounds like a
kludge.

(Please Cc: replies, I'm not subscribed. TIA.)

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