Re: [boost] [review] Fusion review begins:extension.htm:why iterator param Struct?

From: Larry Evans (cppljevans_at_[hidden])
Date: 2006-05-09 11:03:16

On 05/06/2006 05:11 PM, dan marsden wrote:
> Larry Evans wrote:
[snip]
>>Also, since the above code is all for a specific structure, i.e.
>>example_struct, why is there any need for including a Struct
>>template parameter.  Why not just:
>>
>>  template<int Pos>
>>  struct example_struct_iterator
>>      : iterator_base<example_struct_iterator<example_struct, Pos> >
>>  {
>>      BOOST_STATIC_ASSERT(Pos >=0 && Pos < 3);
>>      typedef example_struct struct_type;
>>  ...
>>  };
> 
> 
> The Struct parameter allows us to capture whether the iterator points into
> an example_struct or a const example_struct. Some of the rest of the example
> code needs to make this distinction.
OK, now I see.  Thanks.
> 
> Thanks for the feedback

Sure.  And thanks for the fusion_v2 and the quick response to feedback.

However, I've got another question.  I removed the value_of_impl from my 
code since it looks like deref_impl defines what's needed and
my code ran OK.  Is value_of_impl really needed to define a
fusion iterator for a new struct?