>The new features people ask for never seem to line up with the layers in your code. This has been my biggest objection to many tutorials, videos, and books on

>The new features people ask for never seem to line up with the layers in your code. This has been my biggest objection to many tutorials, videos, and books on OO, architecture, and patterns: They're useful for greenfield code, but so often in large systems, they are nearly impossible of implementation. The trouble, of course, is that it's nearly impossible to teach how to do these things inside large codebases that are layered in ways that don't align with the intended change. Consider that other than Michael Feathers' book, there are few, if any, good books on maintaining code. And so we all struggle, and code becomes progressively more imperative and less coherent.