Guidelines for building dynamically linked libraries

This section gives coding guidelines and maintenance tips for development of dynamically linked libraries. Before getting down to specifics, we should emphasize that if you plan to develop a commercial dynamic shared library, you ought to consider providing a compatible archive as well. As noted previously, some users may not find a dynamically linked library appropriate for their applications. Others may want their applications to run on UNIX operating system releases without shared library support. Dynamically linked (or shared) library code is completely compatible with archive library code. You can use the same source files to build archive and dynamically linked library versions of a library. You can use dynamically linked libraries for the following reasons:

• Because library code is not copied into the executables that use it, they require less disk space.

• Because library code is shared at run time, the dynamic memory needs of systems are reduced.

• Because symbol resolution is put off until run time, dynamically linked libraries can be updated without having to relink applications that depend on them.

• As long as its pathname is not hard-coded in an executable, a dynamically linked library can be moved to a different directory without breaking an application.

To enhance performance of a dynamically linked library, you should:

1. Minimize the library's data segment

2. Minimize paging activity