Heap: container or range?

[Brad Roberts]

Andrei Alexandrescu wrote:
> Sean Kelly wrote:
>> Sean Kelly wrote:
>>> Andrei Alexandrescu wrote:
>>>>
>>>> Ah, never mind all that. I realized that I can't have a heap range.
>>>> This is because heaps must mutate the underlying range in-place and
>>>> any copy will mess the heap up. Here's the example that clarify it
>>>> for me:
>>>>
>>>>         int[] a = [ 4, 1, 3, 2, 16, 9, 10, 14, 8, 7 ];
>>>>         auto h = Heap!(int[])(a);
>>>>         assert(equal(take(5, h) == [ 8, 9, 10, 14, 16 ]);
>>>>
>>>> At this point the mutations done by take messed up h already!!
>>>
>>> Hm... so assuming this is a min heap, I have:
>>>
>>> a = [4,1,3,2,16,9,10,14,8,7];
>>> h = [1,2,3,4,7,9,10,14,8,16];
>>> take(5, h);
>>> h = [8,10,9,16,14];
>>>
>>> Shouldn't take call next repeatedly on the heap, which will in turn
>>> perform a popHeap operation?  It's difficult to be sure what the
>>> result will be after take(5,h) occurs, but it should still be a valid
>>> heap, correct?
>>
>> Oh, I would also expect:
>>
>> a = [8,10,9,16,14, garbage];
>>
>> Since it isn't aware of the length adjustment.  Perhaps this is what
>> you meant?
>>
>>
>> Sean
> 
> Yah, that's what I meant. h still thinks its length is 10 and that those
> 10 elements respect the heap property.
> 
> Andrei

Since take is a mutator, that implies that h needs to be a reference
type or a by ref value, right?  So, why not make it so?

Later,
Brad