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Chapter 6 Creating a Model The generator accepts a Virtuoso source file as input. If the Virtuoso source file is reusable, the file is also called a model. A model is reusable because it does not contain specific data names or specific logic. One model may be used multiple times to perform the same logical function but on different data corresponding to different problems. For example, a COBOL model which performs a maintenance transaction on a master dataset may be used to generate a COBOL module to maintain a master dataset in an order entry application or a COBOL module to maintain a master dataset in an inventory application. Models may be reused within an application or from application to application. A model (or a Virtuoso source file) is used to generate a complete structure. A COBOL model is used to generate a COBOL program or subprogram; a documentation model is used to generate a document. Macros, like models, are reusable components, but macros typically perform a much smaller, narrowly-defined operation or function. For example, a macro might create a record, call an intrinsic, or perform error handling. Macros are called from within models and Virtuoso source files to perform a task. Models and macros enhance programmer productivity by providing a mechanism to create reusable components. By placing tested models and macros into your library, you can reduce the amount of time spent in the test/debug phase, since the code generated has already been tested. In addition, models and macros help to establish and implement your organization's standard programming practices. Standardization reduces the variability in individual coding styles and makes maintenance more straightforward. It is up to you to determine whether a piece of code or text is reusable and thus should become a model or a macro. The previous chapters in this manual have discussed the basic features of the Virtuoso Code Generator. This chapter describes how to use these features to create reusable components. The discussion focuses on how to create a model, but the same techniques may be used to create a macro.