To provide an example of the utility of method combinations: I wrote a project skeleton generator[0] whose functionality is provided by progn-composable plugin

To provide an example of the utility of method combinations: I wrote a project skeleton generator[0] whose functionality is provided by progn-composable plugins, implemented as mixin classes. Every bit of functionality, like adding a README.md file to a project skeleton, adding a .gitignore file, adding stub unit tests, etc. is implemented as a mixin class. A full template inherits[1] all the mixins it needs. There is a generic function, render-template[1], that takes a template, some options, and the target directory, and uses the progn method combination. Meaning: every method in the chain is called in succession, and each method adds its own thing to the generated project. The render-template method for the gitignore mixin adds a .gitignore file, for instance. When render template is called on an instance of a class that inherits a bunch of template mixins, it runs all of those mixins in addition to the render-template method of that class itself (if any). In a sense, this is basically the entity-component pattern[3] implemented in the object system itself, with the caveat that you can't have "multiple instances" of the same component -- you can't inherit a class twice. [0]: https://github.com/roswell/mystic https://github.com/roswell/mystic [1]: https://github.com/roswell/mystic/blob/2d0fd8e401d50893b4a15f009dcd3958b7da5e57/templates/library/library.lisp#L17 https://github.com/roswell/mystic/blob/2d0fd8e401d50893b4a15... [2]: https://github.com/roswell/mystic/blob/2d0fd8e401d50893b4a15f009dcd3958b7da5e57/src/mystic.lisp#L123 https://github.com/roswell/mystic/blob/2d0fd8e401d50893b4a15... [3]: https://en.wikipedia.org/wiki/Entity_component_system https://en.wikipedia.org/wiki/Entity_component_system