pl/pgsql breakage in 8.1b4?

Just testing pl/pgsql functions in 8.1beta4, I see failures for syntax that 
works in 8.0.3. The simplest test case for this is:

create table ptest(foo int, bar varchar(10));
create or replace function modify_ptest(foo int,bar varchar)
returns numeric as $$
declare res numeric;
beginupdate ptestset bar = modify_ptest.barwhere foo = modify_ptest.foo;res := 0;
return res;
end;
$$ LANGUAGE plpgsql;

The error message from psql is:

ERROR:  syntax error at or near "$1" at character 19
QUERY:  update ptest set  $1  = modify_ptest.bar where  $2  = modify_ptest.foo
CONTEXT:  SQL statement in PL/PgSQL function "modify_ptest" near line 7
LINE 1: update ptest set  $1  = modify_ptest.bar where  $2  = modify...                         ^

I assume what I'm trying should still work, though I couldn't find comparable 
examples in the doco. Looks to me like a problem with parameter aliasing.

Regards, Philip.

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Utiba Pty Ltd 
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