[Boost-users] [MPL] implementing a "trait"?

Subject: [Boost-users] [MPL] implementing a "trait"?
From: John M. Dlugosz (ngnr63q02_at_[hidden])
Date: 2014-02-04 13:03:40

I want to mark certain types as being of a category of my invention (e.g. is_pretty), for 
purposes of using enable_if in the same manner is standard type traits such as 
is_arithmetic etc.

The trait will be false by default, and I'd declare something to nominate types that 
should be seen to have that trait.  I want it to follow inheritance; if B has been 
declared to be in my category, and C is derived from B, then C will also be in that 
category without needing to do anything more (though some way to turn it _off_ would be 
available).

Can someone advise me on an easy way to structure this?

Thanks,
—John