6.1.4 Embedded Commands

(require 'database-commands)

This enhancement wraps a utility layer on relational-database which provides:

• Automatic execution of initialization commands stored in database.
• Transparent execution of database commands stored in *commands* table in database.

When an enhanced relational-database is called with a symbol which matches a name in the *commands* table, the associated procedure expression is evaluated and applied to the enhanced relational-database. A procedure should then be returned which the user can invoke on (optional) arguments.

The command *initialize* is special. If present in the *commands* table, open-database or open-database! will return the value of the *initialize* command. Notice that arbitrary code can be run when the *initialize* procedure is automatically applied to the enhanced relational-database.

Note also that if you wish to shadow or hide from the user relational-database methods described in Database Operations, this can be done by a dispatch in the closure returned by the *initialize* expression rather than by entries in the *commands* table if it is desired that the underlying methods remain accessible to code in the *commands* table.