I'm implementing some custom memory allocator, is possible to call an object destructor directly?

For example

void deallocate(T)(T object)
{
  assert(object !is null);

  object.~this();
  rawDeallocate(cast(void *)object);
}

On Monday, 21 October 2013 at 02:06:02 UTC, Agustin wrote:
> I'm implementing some custom memory allocator, is possible to call an object destructor directly?


destroy(object);

destroy is in the automatically imported object.dm so you don't have to import anything,

The source code is in dmd2/src/druntime/src/object_.d, there's a few overloads if you are curious how it is implemented. Short answer is there's a pointer to the destructor in the TypeInfo and destroy calls it.

On Monday, 21 October 2013 at 02:17:54 UTC, Adam D. Ruppe wrote:
> On Monday, 21 October 2013 at 02:06:02 UTC, Agustin wrote:
>> I'm implementing some custom memory allocator, is possible to call an object destructor directly?
>
>
> destroy(object);
>
> destroy is in the automatically imported object.dm so you don't have to import anything,
>
> The source code is in dmd2/src/druntime/src/object_.d, there's a few overloads if you are curious how it is implemented. Short answer is there's a pointer to the destructor in the TypeInfo and destroy calls it.

Thank you :)

On Monday, 21 October 2013 at 02:26:03 UTC, Agustin wrote:
> On Monday, 21 October 2013 at 02:17:54 UTC, Adam D. Ruppe wrote:
>> On Monday, 21 October 2013 at 02:06:02 UTC, Agustin wrote:
>>> I'm implementing some custom memory allocator, is possible to call an object destructor directly?
>>
>>
>> destroy(object);
>>
>> destroy is in the automatically imported object.dm so you don't have to import anything,
>>
>> The source code is in dmd2/src/druntime/src/object_.d, there's a few overloads if you are curious how it is implemented. Short answer is there's a pointer to the destructor in the TypeInfo and destroy calls it.
>
> Thank you :)

What about constructor?. My current code is:

	T allocate(T : Object, A...)(auto ref A arguments) {
		auto pMemory = rawAllocate(__traits(classInstanceSize, T), T.alignof); // Return void*

		emplace!T(cast(T *)pMemory, arguments);
		return cast(T) pMemory;
	}

Doesn't seems to work, and i can't find any good documentation about it.

On Monday, October 21, 2013 05:07:02 Agustin wrote:
> What about constructor?. My current code is:
> 
> 	T allocate(T : Object, A...)(auto ref A arguments) {
> 		auto pMemory = rawAllocate(__traits(classInstanceSize, T),
> T.alignof); // Return void*
> 
> 		emplace!T(cast(T *)pMemory, arguments);
> 		return cast(T) pMemory;
> 	}
> 
> Doesn't seems to work, and i can't find any good documentation about it.

IIRC, the constructor should be name __ctor.

- Jonathan M Davis

On Monday, 21 October 2013 at 03:46:33 UTC, Jonathan M Davis wrote:
> On Monday, October 21, 2013 05:07:02 Agustin wrote:
>> What about constructor?. My current code is:
>> 
>> 	T allocate(T : Object, A...)(auto ref A arguments) {
>> 		auto pMemory = rawAllocate(__traits(classInstanceSize, T),
>> T.alignof); // Return void*
>> 
>> 		emplace!T(cast(T *)pMemory, arguments);
>> 		return cast(T) pMemory;
>> 	}
>> 
>> Doesn't seems to work, and i can't find any good documentation
>> about it.
>
> IIRC, the constructor should be name __ctor.
>
> - Jonathan M Davis

no property 'opCall' for type 'Main.MyClass' :(

On Monday, 21 October 2013 at 03:50:24 UTC, Agustin wrote:
> On Monday, 21 October 2013 at 03:46:33 UTC, Jonathan M Davis wrote:
>> On Monday, October 21, 2013 05:07:02 Agustin wrote:
>>> What about constructor?. My current code is:
>>> 
>>> 	T allocate(T : Object, A...)(auto ref A arguments) {
>>> 		auto pMemory = rawAllocate(__traits(classInstanceSize, T),
>>> T.alignof); // Return void*
>>> 
>>> 		emplace!T(cast(T *)pMemory, arguments);
>>> 		return cast(T) pMemory;
>>> 	}
>>> 
>>> Doesn't seems to work, and i can't find any good documentation
>>> about it.
>>
>> IIRC, the constructor should be name __ctor.
>>
>> - Jonathan M Davis
>
> no property 'opCall' for type 'Main.MyClass' :(

Trait allMember return "__ctor", but seems like i cannot call it directly:

(cast(T)pMemory).__ctor(arguments); // Being pMemory void*

On Monday, October 21, 2013 05:53:46 Agustin wrote:
> On Monday, 21 October 2013 at 03:50:24 UTC, Agustin wrote:
> > On Monday, 21 October 2013 at 03:46:33 UTC, Jonathan M Davis
> > 
> > wrote:
> >> On Monday, October 21, 2013 05:07:02 Agustin wrote:
> >>> What about constructor?. My current code is:
> >>> 	T allocate(T : Object, A...)(auto ref A arguments) {
> >>> 
> >>> 		auto pMemory = rawAllocate(__traits(classInstanceSize, T),
> >>> 
> >>> T.alignof); // Return void*
> >>> 
> >>> 		emplace!T(cast(T *)pMemory, arguments);
> >>> 		return cast(T) pMemory;
> >>> 
> >>> 	}
> >>> 
> >>> Doesn't seems to work, and i can't find any good documentation about it.
> >> 
> >> IIRC, the constructor should be name __ctor.
> >> 
> >> - Jonathan M Davis
> > 
> > no property 'opCall' for type 'Main.MyClass' :(
> 
> Trait allMember return "__ctor", but seems like i cannot call it directly:
> 
> (cast(T)pMemory).__ctor(arguments); // Being pMemory void*

If you want to see how to use emplace, I'd advise looking at std.typecons.RefCounted's implementation:

https://github.com/D-Programming-Language/phobos/blob/master/std/typecons.d#L3505

emplace calls the constructor for you, so I don't know why you'd be trying to call it. But you can look at emplace's implementation if you want to see how to call __ctor.

For structs: https://github.com/D-Programming-Language/phobos/blob/master/std/conv.d#L3976

For classes: https://github.com/D-Programming-Language/phobos/blob/master/std/conv.d#L4716

I don't think that it'll work if the constructor is private though, so maybe that's your problem.

- Jonathan M Davis

On Monday, 21 October 2013 at 05:17:01 UTC, Jonathan M Davis wrote:
> On Monday, October 21, 2013 05:53:46 Agustin wrote:
>> On Monday, 21 October 2013 at 03:50:24 UTC, Agustin wrote:
>> > On Monday, 21 October 2013 at 03:46:33 UTC, Jonathan M Davis
>> > 
>> > wrote:
>> >> On Monday, October 21, 2013 05:07:02 Agustin wrote:
>> >>> What about constructor?. My current code is:
>> >>> 	T allocate(T : Object, A...)(auto ref A arguments) {
>> >>> 	
>> >>> 		auto pMemory = rawAllocate(__traits(classInstanceSize, T),
>> >>> 
>> >>> T.alignof); // Return void*
>> >>> 
>> >>> 		emplace!T(cast(T *)pMemory, arguments);
>> >>> 		return cast(T) pMemory;
>> >>> 	
>> >>> 	}
>> >>> 
>> >>> Doesn't seems to work, and i can't find any good documentation
>> >>> about it.
>> >> 
>> >> IIRC, the constructor should be name __ctor.
>> >> 
>> >> - Jonathan M Davis
>> > 
>> > no property 'opCall' for type 'Main.MyClass' :(
>> 
>> Trait allMember return "__ctor", but seems like i cannot call it
>> directly:
>> 
>> (cast(T)pMemory).__ctor(arguments); // Being pMemory void*
>
> If you want to see how to use emplace, I'd advise looking at
> std.typecons.RefCounted's implementation:
>
> https://github.com/D-Programming-Language/phobos/blob/master/std/typecons.d#L3505
>
> emplace calls the constructor for you, so I don't know why you'd be trying to
> call it. But you can look at emplace's implementation if you want to see how
> to call __ctor.
>
> For structs:
> https://github.com/D-Programming-Language/phobos/blob/master/std/conv.d#L3976
>
> For classes:
> https://github.com/D-Programming-Language/phobos/blob/master/std/conv.d#L4716
>
> I don't think that it'll work if the constructor is private though, so maybe
> that's your problem.
>
> - Jonathan M Davis

I'm silly the issue was at this line

		auto pMemory = rawAllocate(__traits(classInstanceSize, T), T.alignof);

		emplace(pMemory, arguments);

Correct was

		auto pMemory = rawAllocate(__traits(classInstanceSize, T), T.alignof);

		emplace(&pMemory, arguments);

Thanks guys

On Monday, 21 October 2013 at 05:40:13 UTC, Agustin wrote:
> On Monday, 21 October 2013 at 05:17:01 UTC, Jonathan M Davis wrote:
>> On Monday, October 21, 2013 05:53:46 Agustin wrote:
>>> On Monday, 21 October 2013 at 03:50:24 UTC, Agustin wrote:
>>> > On Monday, 21 October 2013 at 03:46:33 UTC, Jonathan M Davis
>>> > 
>>> > wrote:
>>> >> On Monday, October 21, 2013 05:07:02 Agustin wrote:
>>> >>> What about constructor?. My current code is:
>>> >>> 	T allocate(T : Object, A...)(auto ref A arguments) {
>>> >>> 	
>>> >>> 		auto pMemory = rawAllocate(__traits(classInstanceSize, T),
>>> >>> 
>>> >>> T.alignof); // Return void*
>>> >>> 
>>> >>> 		emplace!T(cast(T *)pMemory, arguments);
>>> >>> 		return cast(T) pMemory;
>>> >>> 	
>>> >>> 	}
>>> >>> 
>>> >>> Doesn't seems to work, and i can't find any good documentation
>>> >>> about it.
>>> >> 
>>> >> IIRC, the constructor should be name __ctor.
>>> >> 
>>> >> - Jonathan M Davis
>>> > 
>>> > no property 'opCall' for type 'Main.MyClass' :(
>>> 
>>> Trait allMember return "__ctor", but seems like i cannot call it
>>> directly:
>>> 
>>> (cast(T)pMemory).__ctor(arguments); // Being pMemory void*
>>
>> If you want to see how to use emplace, I'd advise looking at
>> std.typecons.RefCounted's implementation:
>>
>> https://github.com/D-Programming-Language/phobos/blob/master/std/typecons.d#L3505
>>
>> emplace calls the constructor for you, so I don't know why you'd be trying to
>> call it. But you can look at emplace's implementation if you want to see how
>> to call __ctor.
>>
>> For structs:
>> https://github.com/D-Programming-Language/phobos/blob/master/std/conv.d#L3976
>>
>> For classes:
>> https://github.com/D-Programming-Language/phobos/blob/master/std/conv.d#L4716
>>
>> I don't think that it'll work if the constructor is private though, so maybe
>> that's your problem.
>>
>> - Jonathan M Davis
>
> I'm silly the issue was at this line
>
> 		auto pMemory = rawAllocate(__traits(classInstanceSize, T), T.alignof);
>
> 		emplace(pMemory, arguments);
>
> Correct was
>
> 		auto pMemory = rawAllocate(__traits(classInstanceSize, T), T.alignof);
>
> 		emplace(&pMemory, arguments);
>
> Thanks guys

That didn't work, but after reading how emplace works, i had to make some changes.

	public T allocate(T : Object, A...)(auto ref A arguments) {
		auto pMemory = rawAllocate(__traits(classInstanceSize, T), T.alignof);
		assert(pMemory !is null, "Not enought memory on the allocator");

		byte[] * pByteMemory = cast(byte[] *) pMemory;
		*pByteMemory = typeid(T).init[];

		auto pObject = cast(T) pMemory;
		static if (is(typeof(pObject.__ctor(arguments))))
		{
			pObject.__ctor(arguments);
		}
		return pObject;
	}

That would work.