From the two chapters that are publically available it seems that he knows what he is talking about.
My current take on codegen is to simply use xslt.
I have an extended xslt utility that I use.
The syntax is:
xslt source transform target [name value]*
This allows one root document to be used to create a batch file that generates the used code from the one core document.
It has a few other tricks (handling or header comments and logging changes), but that is about it.
It does include some string manipulation extensions.