purity and memory allocations/pointers

[John Colvin]

On Saturday, 3 August 2013 at 23:15:25 UTC, John Colvin wrote:
> On Saturday, 3 August 2013 at 21:19:35 UTC, monarch_dodra wrote:
>> On Saturday, 3 August 2013 at 19:07:49 UTC, Meta wrote:
>>> On Saturday, 3 August 2013 at 16:47:52 UTC, Timon Gehr wrote:
>>>> On 08/03/2013 05:59 PM, monarch_dodra wrote:
>>>>> One last question: Pointers.
>>>>>
>>>>> int get(int* p) pure
>>>>> {
>>>>>  return *p;
>>>>> }
>>>>>
>>>>> void main()
>>>>> {
>>>>>  int i = 0;
>>>>>  auto p = &i;
>>>>>  get(p);
>>>>> }
>>>>>
>>>>> Here, get, to me, is obviously not pure, since it depends 
>>>>> on the state
>>>>> of the global "i". *Where* did "get" go wrong? Did I simply 
>>>>> "abusively"
>>>>> mark get as pure? Is the "pure" keyword's guarantee simply 
>>>>> "weak"?
>>>>> ...
>>>>
>>>> Yes, it's weak.
>>>
>>> It depends on whether you think a pointer dereference is pure 
>>> or not (I don't know the answer). That aside, as long as get 
>>> doesn't modify the value at *p or change what p points to, 
>>> this is strongly pure (i.e., the academic definition of 
>>> purity).
>>
>> Thank the 3 of you for your answers. I think I had a wrong 
>> preconception of what pure is. I think this cleared most of it 
>> up.
>
> Is there anywhere formal defining D's pure (weak vs strong 
> etc.)? A page in the wiki perhaps?
>
> Imagine someone new coming to D and being confused by what our 
> purity system is. It would suck to only be able to give an 
> ad-hoc answer or link them to a previous discussion.
>
> I would offer but I don't really understand it myself.

Woops, forgot about this: 
http://klickverbot.at/blog/2012/05/purity-in-d/

Is it still up-to-date?