Re: [Boost-users] [fusion] at_key + for_each

Subject: Re: [Boost-users] [fusion] at_key + for_each
From: Kim Kuen Tang (kuentang_at_[hidden])
Date: 2010-05-04 13:32:24

Christopher Schmidt schrieb:
> Denis Taniguchi schrieb:
>> Hi,
>>
>> I was trying to implement something equivalent to the following piece of
>> code:
>>
>> template<class Field1, class Field2, ... , class FieldN, class Range,
>> class Function>
>> Function for_each(Range&r, Function f)
>> {
>>    using namespace boost;
>>    using namespace boost::fusion;
>>
>>    BOOST_FOREACH(typename range_value<Range>::type&v, r)
>>    {
>>      at_key<Field1>(v) = f(at_key<Field2>(v), at_key<Field3>(v), ... ,
>> at_key<FieldN>(v));
>>    }
>>    return f;
>> }
>>
>> Is there a simple way to do this using fusion's current functionalities?
>
> If you pass Field2...FieldN wrapped in a mpl sequence, its quiete 
> simple. See the attached code for an example implementation.
>
Hi Christopher,

yes, you are right. The function fusion::invoke is able to do it.

However, IMHO using the preprocessor for this paricular situation will 
suit it more.
Just my opinion.

-Kim

> -Christopher
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