cast name to oid

I got my function dump function to work. Enhancing to handle errors if the object doesn't exist.

I want to add an exception block, to trap the object not found error.
But when I changed the input parameter type from regproc to text, I was no longer getting matches.
I am trying to explicitly cast the object name as an oid.
Can someone let me know the correct way to do this?

This is failing
where p.oid = cast(proname as regproc);

NOTICE: found dba_work.pg_get_functiondef2
WARNING: sqlstate 42846
WARNING: sqlerrm cannot cast type text to regproc

Thanks
Current content

CREATE OR REPLACE FUNCTION dba_work.pg_get_functiondef2(proname text)
RETURNS text AS
$BODY1$
declare
xsource text;
begin
if public.ifexists(proname) then
raise notice 'found %', proname;
begin
select into xsource
E'\n'
||'CREATE OR REPLACE FUNCTION '||n.nspname||'.'||p.proname||'('||pg_catalog.oidvectortypes(p.proargtypes)||')'
|| E'\nRETURNS '||t.typname||' AS'
|| E'\n$BODY$\n'
|| prosrc
|| E'\n$BODY$\n'
||' LANGUAGE ''' || l.lanname
|| E''' VOLATILE;'
|| E'\n alter function '||n.nspname||'.'||p.proname||'('||pg_catalog.oidvectortypes(p.proargtypes)||') owner to '||pg_get_userbyid(p.proowner)||';'
|| regexp_replace(replace(E'\n GRANT EXECUTE ON FUNCTION '||n.nspname||'.'||p.proname||'('||pg_catalog.oidvectortypes(p.proargtypes)||') TO '
|| array_to_string(proacl,E'\n GRANT EXECUTE ON FUNCTION '||n.nspname||'.'||p.proname||'('||pg_catalog.oidvectortypes(p.proargtypes)||') TO ')
,' =X',' public=X')
,E'=(.*?)(?:\s|$|\n)',E';\n','g')

from pg_proc p

inner join pg_type t
on p.prorettype = t.oid

inner join pg_namespace n
on p.pronamespace = n.oid

inner join pg_language l
on p.prolang = l.oid

where p.oid = cast(proname as name);

Exception
when others Then
xsource = 'Object:'||proname||' not found';
raise warning 'sqlstate %', SQLSTATE;
raise warning 'sqlerrm %', SQLERRM;

end;
end if;

return xsource;
end;

$BODY1$
LANGUAGE plpgsql STABLE;
ALTER FUNCTION dba_work.pg_get_functiondef2(text)
OWNER TO dlittle;

Doug Little

Sr. Data Warehouse Architect | Business Intelligence Architecture | Orbitz Worldwide
500 W. Madison, Suite 1000 Chicago IL 60661| Office 312.260.2588 | Fax 312.894.5164 | Cell 847-997-5741
Douglas(dot)Little(at)orbitz(dot)com<mailto:Douglas(dot)Little(at)orbitz(dot)com>
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