binary expression...

[captain_fid via Digitalmars-d-learn]

Please forgive if asked before. My google skills seemed to fail 
me and didn't see any result from search.

My problem is simple (though not my understanding LOL).
struct D {
      int value;
      bool opEquals()(bool value) const { return (value == 
value); }
}

D aD;
if (aD == 1) { // OK
}

if (aD) {      //  Error: expression aD of type D does not have a 
boolean value
}

Is there a way to overload for this? What am I missing?