m4_comment([$Id: db_cxx.so,v 11.9 2000/03/22 22:02:14 bostic Exp $])m4_ref_title(Upgrading m4_db Applications,    Release 3.0: the Db class for C++ and Java,,    upgrade.3.0/dbenv_cxx, upgrade.3.0/cxx)m4_p([dnlThe static Db::open method and the DbInfo class have been removed in them4_db 3.0 release.  The way to open a database file is to use the new Dbconstructor with two arguments, followed by set_XXX methods to configurethe Db object, and finally a call to the new (nonstatic) Db::open().  Incomparing the m4_db 3.0 release open method with the 2.X static openmethod, the second argument is new.  It is a database name, which canbe null.  The DbEnv argument has been removed, as the environment is nowspecified in the constructor.  The open method no longer returns a Db,since it operates on one.])m4_p([dnlHere's a C++ example opening a m4_db database using the 2.X interface:])m4_indent([dnl// Note: by default, errors are thrown as exceptionsDb *table;Db::open("lookup.db", DB_BTREE, DB_CREATE, 0644, dbenv, 0, &table);])m4_p([dnlIn the m4_db 3.0 release, this code would be written as:])m4_indent([dnl// Note: by default, errors are thrown as exceptionsDb *table = new Db(dbenv, 0);table-__GT__open("lookup.db", NULL, DB_BTREE, DB_CREATE, 0644);])m4_p([dnlHere's a Java example opening a m4_db database using the 2.X interface:])m4_indent([dnl// Note: errors are thrown as exceptionsDb table = Db.open("lookup.db", Db.DB_BTREE, Db.DB_CREATE, 0644, dbenv, 0);])m4_p([dnlIn the m4_db 3.0 release, this code would be written as:])m4_indent([dnl// Note: errors are thrown as exceptionsDb table = new Db(dbenv, 0);table.open("lookup.db", null, Db.DB_BTREE, Db.DB_CREATE, 0644);])m4_p([dnlNote that if the dbenv argument is  null, the database will not existwithin an environment.])m4_page_footer