Re: [Boost-Users] Iterator Adaptor?

From: Duane Murphy (duanemurphy_at_[hidden])
Date: 2002-03-26 23:17:26

--- At Tue, 26 Mar 2002 17:18:20 -0800, David Brownell wrote:

>I have a hunch that this has been asked before, but I can't seem to find
>the answer.  I have a struct similar to:
>
>struct MyStruct
>{
>	int		i;
>	char		c;
>};
>
>And a functor similar to:
>
>struct MyFunctor
>{
>	void operator()(int i)
>	{
>		//Do something with i
>	}
>};
>
>Given a container of MyStruct objects, how can I use iterator_adaptor to
>use MyStruct::i with MyFunctor?  Something like:
>
>std::vector<MyStruct>    v;
>std::for_each(v.begin(), v.end(), MyFunctor());
>
>I have overridden the dereference method in default_iterator_policies to
>return the integer, but am at a bit of a loss where to go from here.
>
>Am I on the right track?

Try taking a look at projection_iterator_adaptor or
transform_iterator_adaptor in the documentation and examples for
iterator_adaptor. I think the project adaptor is what you want. However,
I have had problems getting this to work. Usually I end up with a strange
typing problem associated with taking a reference; I havent spent the
time to track down what is really happening. 

In those cases, I usually turn to the transform_iterator_adaptor. It
usually works fine.

 ...Duane

-- 
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