From: Eric Niebler (eric_at_[hidden])
Date: 2007-04-04 14:20:47
Larry Evans wrote:
> On page:
>
> http://boost-sandbox.sourceforge.net/libs/proto/doc/html/boost_proto/user_s_guide/quick_start.html
>
> the sentence:
>
> Notice that in order to build a Proto expression template, at least
> one argument in the expression must be a Proto-ified. In this case,
> that is done with the terminal<> class template, which is used to
> wrap std::cout.
>
> was, at first, unclear to me because evaluate just had one argument;
> however, "one argument in expression" suggests there could be more
> than one.
>
> The following would be clearer to me:
>
> Notice that in order to build a Proto expression template, at least
> one subexpression of the whole expression must be a Proto-ified. In
> the case of:
>
> cout_ << "hello" << ',' << " world"
>
> this one Proto-ified subexpression is cout_, which is the
> Proto-ification of std::cout via wrapping by the terminal<> class
> template.
>
> I hope that's right. If not, then I still don't know what the
> sentence means :(
Yeesh, I was being very imprecise. Your's is an improvement, but it's
still not completely accurate. It needs to say that for any /operator/
in an expression, at least one operand must be proto-ified. Otherwise,
proto's operator overloads will not be found.
-- Eric Niebler Boost Consulting www.boost-consulting.com