C libraries have a pattern of
----
HiddenType* getObj();
void freeObj(HiddenType*);
----
Is there any way I can make the GC search for a "HiddenType*" and run "freeObj" when the pointer is not found.

On 04/19/2015 04:38 PM, Freddy wrote:
> C libraries have a pattern of
> ----
> HiddenType* getObj();
> void freeObj(HiddenType*);
> ----
> Is there any way I can make the GC search for a "HiddenType*" and run
> "freeObj" when the pointer is not found.

Not automatically. Check out addRange and addRoot:

  http://dlang.org/phobos/core_memory.html

Ali

On Sun, 19 Apr 2015 23:38:47 +0000, Freddy wrote:

> C libraries have a pattern of ----
> HiddenType* getObj();
> void freeObj(HiddenType*);
> ----
> Is there any way I can make the GC search for a "HiddenType*" and run "freeObj" when the pointer is not found.

wrap it in class/struct and run `freeObj()` in destructor.

On Monday, 20 April 2015 at 02:56:35 UTC, Ali Çehreli wrote:
> Not automatically. Check out addRange and addRoot:
>
>   http://dlang.org/phobos/core_memory.html
>
> Ali
The destructor doesn't seem to be running
----
import std.stdio;
import std.c.stdlib;
import core.memory;
struct Test{
	~this(){
		writeln("free: ",&this);
		free(&this);
	}
}

void main(){
	auto ptr=cast(Test*)malloc(4);
	writeln("create: ",ptr);
	GC.addRange(ptr,0,typeid(Test));
	ptr=null;
	GC.collect();
}
----
$ rdmd test
create: 1EEC730

On 04/20/2015 02:48 PM, Freddy wrote:
> On Monday, 20 April 2015 at 02:56:35 UTC, Ali Çehreli wrote:
>> Not automatically. Check out addRange and addRoot:
>>
>>   http://dlang.org/phobos/core_memory.html
>>
>> Ali
> The destructor doesn't seem to be running

Sorry, I misunderstood you. You can use a RAII object as ketmar said:

import std.stdio;
import std.c.stdlib;

struct Test{
    void* ptr;

    ~this(){
        writeln("free: ",&this);
        free(ptr);
    }
}

void main(){
    auto ptr=cast(Test*)malloc(4);
    writeln("create: ",ptr);

    auto test = Test(ptr);  // <-- The dtor of this object will free
}

Ali

On Monday, 20 April 2015 at 22:24:53 UTC, Ali Çehreli wrote:
> On 04/20/2015 02:48 PM, Freddy wrote:
>> On Monday, 20 April 2015 at 02:56:35 UTC, Ali Çehreli wrote:
>>> Not automatically. Check out addRange and addRoot:
>>>
>>>  http://dlang.org/phobos/core_memory.html
>>>
>>> Ali
>> The destructor doesn't seem to be running
>
> Sorry, I misunderstood you. You can use a RAII object as ketmar said:
>
> import std.stdio;
> import std.c.stdlib;
>
> struct Test{
>     void* ptr;
>
>     ~this(){
>         writeln("free: ",&this);
>         free(ptr);
>     }
> }
>
> void main(){
>     auto ptr=cast(Test*)malloc(4);
>     writeln("create: ",ptr);
>
>     auto test = Test(ptr);  // <-- The dtor of this object will free
> }
>
> Ali
I believe your original understanding was right.I want to have HiddenType* be garbage collected and finalized(freed,destructed) when no more references to it are found(stack or heap). I could use reference counting but it seems inefficient for a program rarely collecting and constantly coping.

On Sunday, 19 April 2015 at 23:38:49 UTC, Freddy wrote:
> C libraries have a pattern of
> ----
> HiddenType* getObj();
> void freeObj(HiddenType*);
> ----
> Is there any way I can make the GC search for a "HiddenType*" and run "freeObj" when the pointer is not found.

You can't turn an arbitrary pointer into a garbage collected object.
What you can do, is putting the pointer into a GCed object.

class Wrapper {
  this(HiddenType* p) { _p = p; } }
  ~this() { freeObj(_p); }
  alias _p this;
}

auto obj = new Wrapper(getObj());

Since 2.067.0 we also finalize heap allocated structs, so the wrapper can also be a struct.