From: Maurizio Vitale (mav_at_[hidden])
Date: 2007-04-26 18:08:24
Eric Niebler <eric_at_[hidden]> writes:
> No, proto::_ is a placeholder. And proto::not_<> can logically negate
> any grammar, not just proto::_.
FWIW I kind of like proto::_. It gives me warm memories of ML and Haskell patterns
in the land of...brrr...I digress.
But I'd appreciate if you could elaborate on why you see it as a placeholder.
Technically I guess it is: it certainly takes space in the parse tree, but I tend to
think about placeholders as things that mark a spot that I can then reference
from somewhere else (and from here stems my confusion on transformations from
another thread. This and the fact that mpl lambda placeholders are mentioned in
Now I see proto::_ more like a wildcard pattern that matches anything but doesn't
have additional meaning (or features for the user).
Is there anything I'm missing about proto::_ ?
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