Yeah, polluting the signatures is a shame. I've only just decided that I enjoy using this pattern so my internal standards committee hadn't progressed to the p

Yeah, polluting the signatures is a shame. I've only just decided that I enjoy using this pattern so my internal standards committee hadn't progressed to the proposal stage yet. :) Your syntax makes perfect sense to me, and I think it would make a great addition to the language. I wonder what the real working group would say. (I tried quickly googling for something that might sound like an existing proposal but came up empty.)