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Subject: Re: [boost] [mpl]iter_fold_if Forward Backward rationale?
From: David Abrahams (dave_at_[hidden])
Date: 2009-04-08 11:35:21


on Sun Apr 05 2009, Larry Evans <cppljevans-AT-suddenlink.net> wrote:

> Just as the ForwardPredicate is "augmented" with protection
> against dereferencing the end<numbers>::type in this code:
>
> https://svn.boost.org/trac/boost/browser/trunk/boost/mpl/iter_fold_if.hpp#L42
>
> shouldn't the BackwardPredicate also be augmented with the same
> protection here:
>
> https://svn.boost.org/trac/boost/browser/trunk/boost/mpl/iter_fold_if.hpp#L77

Well, it doesn't need to be; if it did, tests and uses wouldn't compile
;-)

Just think about how you'd implement it and it should become obvious why.

-- 
Dave Abrahams
BoostPro Computing
http://www.boostpro.com

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