Inspecting a DB - psql or system tables ?

Suppose you want to write a program that connects to a
PostgreSQL database and lists its tables and views, the type of
their columns and their relationships (REFERENCES) for automatic
joins.

Would you look at the system tables (pg_class et al.) or the
output of psql \d, \dt, etc ?

While parsing the output of psql is cumbersome, accessing the
system tables seems more likely to break whenever a new version
of PostgreSQL comes out.

--
André Majorel http://www.teaser.fr/~amajorel/