Re: [boost] GSoC 2010: Heaps and Queues

Subject: Re: [boost] GSoC 2010: Heaps and Queues
From: Stewart, Robert (Robert.Stewart_at_[hidden])
Date: 2010-04-07 15:21:59

Dan Larkin wrote:
> Andrew Sutton wrote:
> > Not really "internal", just pointer-like. Typically they're used for
> > iterating -- you can tell by the name :) but they're also used in
> > pointer-like ways. Look at the STL list interfaces,
> > especially insert() and erase().
>
> Okay, so once again, focusing on studying for my exam tonight
> right now,
> but just doing a bit of research to get the gears turning in the
> background.  Standard iterator functionality requires '++',
> '--', '==',
> 'begin()', and 'end()', correct?  Did I miss anything?

It really depends upon the iterator category as to which operations are required.  However, you certainly missed the dereferencing operator.

> Other than that, I'm still a confused about the behavior of iterators
> within partially ordered data structures.  It's one thing to have a
> pointer abstraction, but traversal seems to be an issue.  In
> particular,
> if any changes to the structure are made during the traversal, the
> structure could re-arrange itself in such a way that individual nodes
> could be traversed multiple times before others are visited once,
> without any changes to the node value itself.  This seems like poor
> behavior to me, and I'm not sure what to do with it.  Perhaps someone
> could shed some light on the issue?

You define which container operations invalidate iterators and its up to clients to avoid those operations while iterating.

_____
Rob Stewart                           robert.stewart_at_[hidden]
Software Engineer, Core Software      using std::disclaimer;
Susquehanna International Group, LLP  http://www.sig.com

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