Re: [boost] [mpl]iter_fold_if Forward Backward rationale?

Subject: Re: [boost] [mpl]iter_fold_if Forward Backward rationale?
From: Larry Evans (cppljevans_at_[hidden])
Date: 2009-04-09 07:11:01

On 04/08/09 10:35, David Abrahams wrote:
> 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.
> 
David,

With the change shown in attachment, the mpl tests
passsed, as shown in the vault's:

   Template Metaprogramming/bjam.iter_fold_if_protected.out

-regards,
Larry

P.S.  AFAICT they passed because I saw no **failed**
in the .out file.