Re: [boost] [fusion] for_each

Subject: Re: [boost] [fusion] for_each
From: Christophe Henry (christophe.j.henry_at_[hidden])
Date: 2010-10-05 17:42:21

>> I have 2 fusion containers: a small vector (my_vec) and a bigger set
>> (my_set). I want to overwrite the elements of the set with elements
>> from the vector whenever they have the same type. Sounds simple:
>>
>> struct update
>> {
>>           update(my_set_type&  to_overwrite_):to_overwrite(to_overwrite_){}
>>           template<typename T>
>>           void operator()(T&  elt) /*const?*/
>>           {
>>               boost::fusion::at_key<T>(to_overwrite)=elt;
>>           }
>>           my_set_type&  to_overwrite;
>> };
>>
>> boost::fusion::for_each(my_vec,update(my_set));
>>
>> Except that this won't compile because the operator() is required to
>> be const, which is sad, because it was very simple.
>
> And it won't compile *with* the const?  I don't think the const'ness of
> the member function affects the const'ness of the referent of to_overwrite.

No, it won't compile ;-)