John Carmack applauds D's pure attribute

[Martin Nowak]

On Sun, 26 Feb 2012 20:26:41 +0100, Walter Bright  
<newshound2 at digitalmars.com> wrote:

> On 2/26/2012 7:04 AM, Simon wrote:
>> On 26/02/2012 03:22, Walter Bright wrote:
>>> On 2/25/2012 4:01 PM, Simon wrote:
>>>> On 25/02/2012 22:55, Walter Bright wrote:
>>>>> Enter C++'s shared_ptr. But that works by, for each object,  
>>>>> allocating a
>>>>> *second* chunk of memory to hold the reference count. Right off the  
>>>>> bat,
>>>>> you've got twice as many allocations & frees with shared_ptr than a  
>>>>> GC
>>>>> would have.
>>>>
>>>> http://www.boost.org/doc/libs/1_43_0/libs/smart_ptr/make_shared.html
>>>>
>>>> so you don't have to have twice as many allocations.
>>>
>>> There are many ways to do shared pointers, including one where the
>>> reference count is part of the object being allocated. But the C++11
>>> standard share_ptr does an extra allocation.
>>
>> The stl one is based on boost, so it has make_shared as well:
>>
>> http://en.cppreference.com/w/cpp/memory/shared_ptr
>>
>> and it's in vs 2010
>>
>> http://msdn.microsoft.com/en-us/library/ee410595.aspx
>>
>> Not that I'm claiming shared pointers are superior to GC.
>
> At the GoingNative C++ conference, the guy who is in charge of STL for  
> VS said that it did an extra allocation for the reference count.

It's actually quite nice to combine unique_ptr and shared_ptr.
One can lazily create the refcount only when the pointers are shared.
Often one can get away with unique ownership.

https://gist.github.com/1920202