Re: [boost] Re: A class template for an N-dimensional generic resizable array

From: Kevlin Henney (kevlin_at_[hidden])
Date: 2000-12-04 10:17:31

In message <002201c05e00$59633a20$460a10ac_at_[hidden]>, Kris Thielemans
<kris.thielemans_at_[hidden]> writes
>- multi-dimensional arrays needn't be 'regular' or 'rectangular'. For
>instance, a each index in a 2D array can give you a 1D array with different
>sizes

Ragged arrays, ie like vector< vector<T> >, solve a different design
problem to the one solved by Giovanni's code. Whilst I think there is a
place for them, the constraint of regularity is important in the current
design. Perhaps you would consider a separate proposal?

>- I allow indices with non-zero offset

For any particular reason?

>- there is some extra code like operator+ etc and (binary) IO (but that's
>pretty trivial to add).

What do you do for the ragged cases with operator+, ie where you add two
arrays together and a position is filled in one but not the other? Given
the different possibilities, I'm inclined to think of these options as
expressed through separate algorithm functions rather than a single
operator+.

>The 1st property was required by our application, and does complicate
>optimisation of various operations.

Giovanni's current proposal has a number of strengths, as I see it,
including efficiency and simplicity.

>To solve the issue of 2 types of iterators I have different members:
>
>// iterators for a 1D view on the nD array, so 'pointing' to a T
>inline full_iterator begin_all();
>inline full_iterator end_all();
>
>// iterators which 'point' to a N-1-dim Array.
>inline iterator begin();
>inline iterator end();

Yes, this seems good.

>- it should all have been derived from valarray (but that wasn't around yet
>when I started this project).

No, what you did first seems like the right thing ;->

Kevlin
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