Heap allocation and internal pointers

[Steven Schveighoffer]

On Mon, 20 Jan 2014 11:35:10 -0500, Dmitry Olshansky  
<dmitry.olsh at gmail.com> wrote:

> 19-Jan-2014 20:18, monarch_dodra пишет:

>>
>> My usecase is pretty trivial: A linked list. This is often implemented
>> as a "single" sentinel that serves as both pre-head/post-tail. When the
>> list is empty, the sentinel simply points to itself.
>>
>
> You could use internal pointers for this case as long as:
> a) The struct will never get copied and/or moved. No pass by value, only  
> pointers.
> b) It's out of GC control and in particular GC-allocated built-in arrays.

I think this is somewhat too general. It can be GC allocated, even  
GC-array allocated. The GC will not move around your array unexpectedly  
without updating the pointers.

What you cannot do is array *operations* that might copy the data for that  
reference/slice. So aside from the original 'new' call, you cannot use  
.dup, .idup, .length +=, ~ or ~=, .reserve.

That being said, avoiding using an array is likely to be a better choice :)

As a hint, dcollections does exactly what you want to do, and I've never  
had a problem with it.

-Steve