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From: Andrew Hain (andrew.hain_at_[hidden])
Date: 2008-08-31 09:52:23

Thorsten Ottosen <thorsten.ottosen <at>> writes:

> Andrew Hain skrev:
> > Two quick queries.
> >
> > Would it make sense to have the iterator increment and decrement operators
> > begin() member function of ptr_vector< nullable<> > skip missing records so
> > that applications have no need to check?
> Well, it is always a design trade-off. If we did that, then people who
> need to know the index of the null value is in trouble.
> I do think it would make sense to add some utility iterator/range:
> boost::ptr_vector<T> vec;
> ...
> BOOST_FOREACH( T& e, boost::filter_nulls(vec) )
> or something. I'm open to naming ideas

Something like that could be useful.

> > What is stopping pointer container classes from being used with opaque
> > as a compilation firewall?
> Can you be more specific? I have some trouble knowing the precise problem.

I have been looking at replacing a homebrewed template class with ptr_vector.
The homebrewed template supports opaque classes with a nasty trick that only
allows the template to be used with types known to its definition; this is one
of the reasons I am trying to replace it. During my test I created a clone
template that calls a Clone() member function in each class and I got compiler
errors when the class arguments to ptr_vector are undefined. Would opaque
classes work with a separate out-of-line definition of each class?

> Thanks
> -Thorsten
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