typeoid by name for PG72

Hello, I'm trying to make an array constructor function
work for PGSQL from 72 to 80.
My current problem is that in PG73 the ArrayType structure
wants an elementtype but FmgrInfo does not contain the Oid
of the given argument (only of the function).

Is there an "easy" way to either:
- obtain OID of a given argument
- obtain OID of a given type by its name

By "easy" I mean not involving a query to the backend.

--strk;

For standing up against patentability of software,

Thank You, Poland!

Read the intervention: http://kwiki.ffii.org/ConsPolon041221En
Send your thanks: thankyoupoland.info
Read/do more: http://www.noepatents.org/