Bruno Martínez Aguerre ha escrito:
On Thu, 17 May 2007 16:04:57 -0300, JOAQUIN LOPEZ MU?Z <joaquin@tid.es> wrote:
More than a year ago a request was made for Boost.MultiIndx to provide the ability to get an iterator to an element x from x alone:
iterator iterator_to(const value_type& x);
It was me, I think.
Hello Bruno! Yep, it was your request :)
I can provide this functionality in constant time, and the internal implementation is trivial, but I got thinking about the potential use cases for such capability and cannot come up with something convincing.
Do you see usefulness in having iterator_to()? Can you describe a potential usage scenario? At first blush, seems like this is at least as useful as the homonym functionality in Boost.Intrusive, but if you think about the obvious scenarios applying to B.I, it turns out they do not immediately translate to B.MI.
Yes. My use case was http://thread.gmane.org/gmane.comp.lib.boost.devel/136418/focus=136955
However, now that I look at it, it seems iterator_to is not a solution to that problem.
This is exactly what happened to me when I revisited the request to decide on implementing it.
I still think the feature is usefull. For example, you may be forced to pass a raw pointer to a C interface. With iterator_to you can get the position of the element in a collection without overhead.
I guess I'l finally include it, but it'd be so much nicer if we could find a conclusive use case. I've also thought about legacy interfaces requiring raw pointers, if only we could come up with a simple specific scenario on that line. Thank you, Joaquín M López Muñoz Telefónica, Investigación y Desarrollo