Eliminate class allocators and deallocators?

[Ary Borenszweig]

Andrei Alexandrescu wrote:
> grauzone wrote:
>> Andrei Alexandrescu wrote:
>>> Sean Kelly wrote:
>>>> == Quote from Andrei Alexandrescu (SeeWebsiteForEmail at erdani.org)'s 
>>>> article
>>>>> dsimcha wrote:
>>>>>> == Quote from Andrei Alexandrescu 
>>>>>> (SeeWebsiteForEmail at erdani.org)'s article
>>>>>>> It is a bad idea because distinguishing between release of 
>>>>>>> (expensive)
>>>>>>> resources from dangerous memory recycling is the correct way to 
>>>>>>> obtain
>>>>>>> deterministic resource management within the confines of safety.
>>>>>> This is based on two faulty assumptions:
>>>>>>
>>>>>> 1.  Memory is cheap.  (Not if you are working with absurd amounts 
>>>>>> of data).
>>>>>> 2.  Garbage collection is never a major bottleneck.  (Sometimes 
>>>>>> it's a worthwhile
>>>>>> tradeoff to add a few manual delete statements to code and 
>>>>>> sacrifice some safety
>>>>>> for making the GC run less often.)
>>>>> malloc.
>>>>
>>>> So for placement construction of a class, I guess it would look 
>>>> something like:
>>>>
>>>> auto x = cast(MyClass) malloc(MyClass.classinfo.init.length);
>>>> x.__ctor( a, b, c ); // construct
>>>> ...
>>>> x.__dtor();
>>>> free( cast(void*) x );
>>>>
>>>> Is that right?
>>>
>>> Yes, I think so, but I haven't checked all the details. For example 
>>> I'm not sure whether __ctor copies .init over the memory before 
>>> running the user-defined constructor, or expects that to have been 
>>> done already.
>>
>> Apparently it doesn't: 
>> http://www.digitalmars.com/techtips/class_objects.html
>>
>> See, it's even documented.
>>
>> Anyway, does your statement mean that _ctor is officially supported 
>> (by all conform D compilers)?
>>
>> Because, quoting from the page above:
>> "This technique goes "under the hood" of how D works, and as such it 
>> is not guaranteed to work with every D compiler. In particular, how 
>> the constructors and destructors are called is not necessarilly 
>> portable."
> 
> That technique will be used by a library function.

So... the library will be related somehow to the implementing compiler?