i wonder if there are tutorials/books explaining how you create a library/plugin/module for other to implement?

libraries/frameworks like solr, doctrine, codeigniter etc.

cause it seems that they follow the same pattern. having one "bootstrap" file to load configurations, other classes and so on.

i aim to understand the basics, so i can create a such library.

cause at the moment i want to code an address book that other can use. just include a bootstrap file and they are ready to use my classes (like Doctrine).

recommendations of sources to learn these things of stuff?

you experienced guys, how did you learn it?

thanks.