Re: [Boost-users] [iterator] Problems with iterator_facade and const-qualification

Subject: Re: [Boost-users] [iterator] Problems with iterator_facade and const-qualification
From: Jeff Flinn (TriumphSprint2000_at_[hidden])
Date: 2011-05-06 12:59:06

Evan Driscoll wrote:
> I'm trying to use the iterator_facade and am running into trouble. It's 
> not really caused by the iterator_facade, but I figured I'd ask anyway. 
> This takes some explanation, so if anyone reads this, know that I *do* 
> appreciate it. :-)
> 
> TLDR version: I'm getting a compiler error about converting between 
> pointers of iterator_facade<> instantiations with different const 
> qualifications on the value_type. The code's attached, in addition to 
> mostly appearing (with a few minor formatting changes) inline below. 
> Please help me figure out what to do to fix it.
> 
> 
> 
> What I'm doing is a bit roundabout, but here goes.
> 
> One fault with C++ iterators (at least from some point of view) is that 
> if you want to operate on different kinds of iterators you have to care 
> about too much -- you need to know more than just the type that op* 
> returns (which is all you care about most of the time, iterator_traits 
> notwithstanding), but what the underlying iterator type is. This means 
> that if you want to write code that operates on multiple kinds of 
> iterators, it must be a template.

You might google any_iterator, and see how other authors have addressed 
similar problems.

Jeff