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Subject: Re: [boost] [array] assignement operator
From: Stewart, Robert (Robert.Stewart_at_[hidden])
Date: 2009-05-15 12:16:49

vicente.botet wrote:
On Friday, May 15, 2009 11:46 AM
> Is the following more intuitive?
> array<int,10> a;
> array<int, 5> b;
> as_sub_array<0,4>(a) = b;
> // or
> b=as_sub_array<2,6>(a);

I like that idea, though I'd name it "subarray." I'd expect these to fail at compile time:

   subarray<0,4>(a) = b;
   b = subarray<0,4>;

but not these:

   subarray<0,5>(a) = b;
   b = subarray<0,5>(a);

Thus, I see subarray as having its size specified by the second template parameter and the offset into the array as the first template parameter.

This should also be possible:

   subarray<6,3>(a) = subarray<1,3>(b);

Notice how the "3" matches in that statement, clearly showing that the two subarrays have the same length.

> > The suggested idea may have its uses, but it has
> sufficiently odd behavior that it ought not to be a member
> function and certainly not the copy assignment operator.
> Perhaps a free function is in order.
> Do you think that an specialization of a assign_to function
> would be intuitive
> array<int, 5> a;
> array<int, 2> b;
> // ...
> assign_to(b,a);
> // or
> assign_to(b,as_sub_array<0,1>a);

I don't like that. The argument order isn't intuitive and the odd behavior isn't made clear by the name. Besides, I think subarray handles every use case and makes the subset assignment behavior clear.

Rob Stewart robert.stewart_at_[hidden]
Software Engineer, Core Software using std::disclaimer;
Susquehanna International Group, LLP

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