Re: [Boost-users] [iterator] transform_iterator

Subject: Re: [Boost-users] [iterator] transform_iterator
From: Max (loadcom_at_[hidden])
Date: 2008-12-24 21:18:12

But another minor thing that I don't understand is why 
the template parameters of the transform_iterator and 
the parameters of its constructor are in the different
order.

If I were the author, I would feel keeping them in the 
same order be more natural and more straightforward.

Perhaps letting Function be the 1st template parameter make
it clearer the behavior of the class? :-)

If this is a too stupid question, just ignore. :-)

Thanks.

B/Rgds
Max

----- Original Message -----
From: Steven Watanabe 
To: boost-users_at_[hidden]
Subject: Re: [Boost-users] [iterator] transform_iterator
Date: 2008-12-25 00:47:36

AMDG

Max wrote:

> I just came across transform_iterator and found it a useful generic tool.
> But is it possible for it to go further to make the following code get 
> compiled and run as expected?
>   

No.

> struct A
> {
>         int i_;
>         A() : i_(0) {}
>         explicit A(int i) : i_(i) {}
> };
>
> const int N = 5;
> A a_list[N] = { A(-3), A(1), A(3), A(2), A(-4) }; 
>
> typedef boost::function fn_t;
>
> // sorting a_list according to the elements' i_ member
> std::stable_sort(boost::make_transform_iterator(a_list, fn_t(boost::bind(&A::i_, _1))),
>         boost::make_transform_iterator(a_list+N, fn_t(boost::bind(&A::i_, _1))), 
>         std::less());
>   

stable_sort assumes that the sort keys are the same as the objects
that it is moving around.

In Christ,
Steven Watanabe


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