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From: David Abrahams (dave_at_[hidden])
Date: 2006-01-08 12:00:27
Eduardo Bezerra <edubez_at_[hidden]> writes:
> I'm having a hard time trying to understand what the placeholders
> _1 and _2 mean in the context of the mpl::fold algorithm.
>>From the Boost.Mpl Reference manual:
> typedef vector<long,float,short,double,float,long,long double> types;
> typedef fold<
> , int_<0>
> , if_< is_float<_2>,next<_1>,_1 >
> BOOST_MPL_ASSERT_RELATION( number_of_floats::value, ==, 4 );
> Could someone give me some help on this ?
http://www.boost-consulting.com/mplbook contains a good explanation.
-- Dave Abrahams Boost Consulting www.boost-consulting.com
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