DBface is a toolkit for designing interfaces to object-oriented databases. It provides users with a set of tools for building custom interfaces with minimal programming. This is accomplished by combining techniques from User Interface Management Systems (UIMS) with a built-in knowledge about the specific kinds of techniques used by object-oriented databases. DBface allows users to create graphical constructs and interactive techniques by taking advantage of an object-oriented database environment and tools. Not only can database tools be used for creating an interface, but information about the interface being built is stored within a database schema and is syntactically consistent with all other schema information. Thus, an interface can deal with data and schema information, including information about another interface. This allows for easy reusability of graphical constructs such as data representations.

Although most programming languages have facilities that allow programmers to define procedures that augment the repertoire of built-in functions, comparatively few programming languages have facilities for defining control operations. This is not surprising, since the number of different control operations that can be comfortably accommodated in most programming languages is relatively small. Expressions in Icon can generate a sequence of results. This adds a dimension to control operations that is lacking in most programming languages and makes programmer-defined control operations interesting and useful. This paper describes such a facility and gives a number of examples of its use, including the definition of argument evaluation regimes.