...

So if you want to extract this, you will have to special-case scoped_channel_value anyway. So in this case you don't need a typedef inside. You can just define a specialization like this:

Template <typename ChannelValue> Struct base_channel_value { typedef ChannelValue type; };

Template <typename ChannelValue, typename MinV, typename MaxV> Struct base_channel_value<scoped_channel_value<ChannelValue, MinV, MaxV> > { typedef ChannelValue type; };

I really have to write that one down. I keep on forgetting this trick.

Thanks ! Maybe this utility structure can be added (like channel_type, etc.) ?