Dynamic expression editor

A system, method, and article of manufacture for intuitively defining new attributes and methods as a function of existing attributes and methods is described. The method comprises the steps of creating a composite object having object elements including methods and attributes combined according to a composition rule, displaying a view of expression elements comprising the attributes and methods of the composite object, defining an object element expression combining at least two of the expression elements, and forming the hybrid object element from the selected expression elements. In one embodiment, a drop-down list is used to select a series of attributes, methods and operators that comprise the expression defining the hybrid element. The apparatus comprises means for performing the operations above, including a computer with a processor and memory coupled to a data storage device and a display. The article of manufacture comprises a tangible embodiment of instructions for performing the foregoing operations.