Preservation of manually written source code in case of repeated code generation

Due to the imperfection of existent application generators, some manual coding is impossible to avoid. The products capable of repeating the generation whilst preserving manually written code are still rare. In this paper, the authors consider various ways to preserve the manually implemented parts of the source code in case of repeated code generation. There follows the description of an originally devised procedure that compares the files produced in subsequent steps of generation to the manually changed files. The procedure has been implemented into a proprietary generator, which generates complete applications in source code, based on source code templates. The algorithm of the procedure is based on some known file comparison algorithms and techniques for isolating differences between files. Specific rules are defined to enable automatic merging of source files. Possible ambiguities are resolved manually in interactive mode. The known limitations and possible improvements of the algorithm are exposed.