Re: [boost] Proposal: Monotonic Containers

Subject: Re: [boost] Proposal: Monotonic Containers
From: Peter Bindels (dascandy_at_[hidden])
Date: 2009-06-10 04:33:22

Hi Christian,

2009/6/10 Christian Schladetsch <christian.schladetsch_at_[hidden]>

> There is a case for:
>
> boost::monotonic::inline_storage<N> storage;
> std::vector<int, boost::monotonic::allocator<int> > v(storage); // (A)
>
> versus:
> boost::monotonic::inline_storage<N> storage;
> boost::monotonic::vector<int> v(storage); // (B)
>
> but what about:
> boost::monotonic::inline_storage<N> storage;
> boost::monotonic::map<int, float> v(storage);
>
> versus:
> boost::monotonic::inline_storage<N> storage;
> std::map<int, float, std::less<int>, boost::monotonic::allocator<int> >
> v(storage);
>
> My main concern would be that people just aren't comfortable with the idea
> of using custom allocator types, but they will accept the idea of needing
> to
> pass the storage in once they realised that they needed a monotonic
> container.
>
> There are other important issues, like having to give the predicate type
> for
> the associative containers first.
>
> If I didn't think it was important, I wouldn't have proposed the library in
> the first place. Given that I think that it's important, it is also
> important to me that the usage is clean. (A) above may be `better`,  but
> (B)
> is cleaner.

I much prefer using a standard template library container to any other, even
if it's the same thing but different. I would therefore much prefer the
std::map<int, float, std::less<int>, ...> approach to creating another
container; especially as this one can also take a different comparison
operator.

My rationale is that when I want a vector with a different allocation
scheme, I like to say "vector with a different allocation scheme" rather
than "differently-allocated not-quite-a-std::vector".

Kind regards,
Peter Bindels