Manual memory management in D2

[Andrei Alexandrescu]

On 07/13/2010 04:15 PM, Vladimir Panteleev wrote:
> On Tue, 13 Jul 2010 23:16:30 +0300, Andrei Alexandrescu
> <SeeWebsiteForEmail at erdani.org> wrote:
>
>>>> Not quite. New is different because it is a primitive - it can't be
>>>> implemented as a function (well it could if it user placement new, but
>>>> we're back to square one). In contrast, delete already knows the type
>>>> of the object it's destroying and can call the destructor manually so
>>>> it is easy to implement as a regular function.
>>>
>>> Sorry, not following you here. Why can't new be implemented as a
>>> templated function which takes the type of the object to create as a
>>> template parameter? Isn't it just allocation, copying over T.init, then
>>> calling the constructor with whatever arguments the user passed?
>>
>> In D it's possible to call the constructor by issuing __ctor(). In C++
>> there is no way, hence the presence of a language primitive.
>
> Doesn't that only support my argument that new *can* be implemented as a
> function?

It does. I was explaining how come new was a keyword in C++ followed 
then by imitation by Java (where it's completely unneeded) and D.

>> You should use malloc() and free() for manual memory management and
>> the GC for automatic memory management. Each of these two is
>> ill-suited for carrying the other's job.
>
> Thanks, that was really what I was missing from the picture.
>
> However, D allows overloading new/delete for custom allocators[1] - this
> can be used for a cleaner way to allocate objects in unmanaged memory. I
> don't see why this use of the delete keyword should be deprecated.
>
> [1]: http://digitalmars.com/d/2.0/memory.html#newdelete

That's gone too. It was a thoroughly mistaken feature, and it's an 
accident that it still compiles and runs.

We need to plug all the holes in the dam(n).


Andrei