Instructions for creating an extension data to create instances of an object with additional attributes without creating a new object type

摘要

A computer application product 16 is produced by writing instructions which call functions and data from a tool kit product 4 and functions and data from a plug-in 22, 32. In order to enable object instances to be created with attributes other than those defined by the tool kit developer, each function from the tool kit 4 for creating an object instance has associated therewith an extension record 8-1 which can be amended to store data from which further instructions from a plug-in 22, 32 for creating an additional attribute for the object instance can be determined. When the application product is run, an object instance is created using instructions from the tool kit 4, and the extension record is checked to see if any additional attributes are to be created for the object instance and, if they are, the additional attribute(s) are created using instructions from the plug-in 22, 32.