Re: [Boost-users] std::list customization

Subject: Re: [Boost-users] std::list customization
From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2010-01-30 13:10:28

AMDG

Etienne Philip Pretorius wrote:
> I know this is not boost specific, but I would appreciate any comments 
> about the following.
>
> I have a specific set of values stored in a std::list<unsigned char>. 
> As expected I can delete and add items anywhere, since I am using the 
> std::list object rearrange its own contents. But here is the problem - 
> when I have already decided that item at position 13 should always 
> remain at position 13 if the list has 13 or more objects in it...
>
> If I remove an item from the beginning then the item at position 13 
> becomes the item at position 12, while this is undesired - the effect 
> of shifting everything else on by one value is desired.
>
> Some examples of what I require:
>
> Fixed position marked with [].
>
> a,b,c,[d],e,f
>
> pop_front() is called
>
> b,c,e,[d],f
>
> This list object should also work when inserting items and keep those 
> with fixed positions at their position if the object size allows it.
>
> Any suggestions, Ideas on how to implement this would be greatly 
> appreciated.

You could use Boost.Intrusive to superimpose a second list
containing just the fixed position elements.  You'll have to
implement wrappers for all the mutating operations that do
appropriate fixing up.

In Christ,
Steven Watanabe