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17.5 A Simple GNU/Linux Dynamic Module
As an appetiser for working with dynamic loadable modules, here is a minimal module written for the interface used by the loader in the previous section:
Again, to compile on a GNU/Linux machine:
Having compiled both loader and module, a test run looks like this:
If you have a GNU/Linux system, you should experiment with the simple examples from this chapter to get a feel for the relationship between a dynamic module loader and its modules -- tweak the interface a little; try writing another simple module. If you have a machine with a different dynamic loading API, try porting these examples to that machine to get a feel for the kinds of problems you would encounter if you wanted a module system that would work with both APIs.
The next chapter will do just that, and develop these examples into a fully portable module loading system with the aid of GNU Autotools. In 20.1 A Module Loading Subsystem, I will add a more realistic mdoule loader into the Sic project last discussed in 12. A Large GNU Autotools Project.