Gentoo Eclass Writing Guide

http://devmanual.gentoo.org/eclass-writing/index.html
bitbake的资料确实很少，而其代码写的很少注释，所以，只能从源头追踪，bitbake/oe源于gentoo,而gentoo有很多的资料，最近在研究bitbake bbclass,所以现在来研究下gentoo的class---eclass

An eclass may provide default implementations for any of the standard ebuild functions (src_unpack, pkg_postinst etc). This can be done either as a simple function definition (which is not multiple eclass friendly) or using EXPORT_FUNCTIONS. Functions given to EXPORT_FUNCTIONS are implemented as normal, but have their name prefixed with ${ECLASS}_.

也就是说在bbclass中，既可以提供标准的函数 do_configure,do_compile,do_install,等等，也可以自己定义一些普通的函数使用，我再继续研究....