aggregate over tables in different schema

I've tables in different schemas all with the same name and
structure.
I'd like to compute an aggregate on the union of those tables.
I don't know the schemas in advance.
The list of the schema will be built selecting all the schemas that
contain a table with that name.

Other than building dynamically the statement as a list of union or
building up a view is there any other way?

--
Ivan Sergio Borgonovo
http://www.webthatworks.it