Is this thread here to increase visibility for the issue at hand with current macros even more? 
I think the proposal for Export Macros is actually almost there already. It seems to solve the glaring hole with the missing possibility to export generated definitions form a macro scope. The facility to generate definitions at all is already included in the current macro features. Making those definitions visible to the “outside world” is the (only?) missing part, and export macros would solve this as I understand.
Also the discussion whether generated code should be purely “virtual” or written to disk seems to be related here. There seem to be divergent opinions on that topic.