The Presentation Manager application model affords the opportunity for significant standardization and reuse of application code, at both the application object and function levels. The dynamic linking facilities provided by OS/2 allow this capability to be carried over to executable code as well as source code. Such reusability reduces the amount of new code required for applications, thereby reducing the development time and cost of new applications.
Common application elements such as windows and dialogs may be defined and stored in dynamic link libraries for access by one or more applications, thus implementing reusability at the application object or dialog level. At a lower level, a large number of common Presentation Manager application tasks may be identified, which may also be placed in standard routines for purposes of enhancing programmer productivity.
A further benefit of using standardized routines is the improvement in the consistency of both the application code and the user interface. Such standardization provides an easy means of enforcing Systems Application Architecture CUA standards without the need for programmers to repetitively code definitions for an CUA-conforming user interface. In addition, the standardized implementation of various functions and techniques eases the task of application maintenance, since all applications will behave in a similar manner through the use of common code.
Although the functions mentioned in this chapter are restricted to Presentation Manager functions, the same principles may be applied to other functions, dialogs etc., which are common to multiple applications within the organization. The creation of standard routines for such functions, and the incorporation of these routines into dynamically linked modules under OS/2, may enhance the modularity and granularity of applications and bring additional benefits through reduced development time for new applications, and through easier application maintenance and change management.