Keeping a list of instances and garbage-collection

[Sergey Gromov]

Sun, 29 Mar 2009 17:42:48 -0400, Chad J wrote:

> Simon TRENY wrote:
>> Hello,
>> 
>> I have a class "A" and I'd like to keep a list of all the created instances of this class. To do that, I have a static List!(A) in the A class and, in the constructor, I add each new instance to this list. This gives me the following code:
>> 
>> class A {
>>    private static List!(A) s_instances;
>> 
>>    public this() {
>>       s_instances.add(this);
>>    }
>> 
>>    public ~this() {
>>       s_instances.remove(this);
>>    }
>> 
>>    public static void printAll() {
>>       foreach (A instance; s_instances)
>>          print(instance.toString());
>>    }
>> }
>> 
>> But then, since all the instances are referenced by the static list, they are never garbage-collected, which could be a problem. In some other languages, this can be solved using weak references, but I haven't found any informations about using weak references in D. Is there any way to solve this problem?
>> 
>> Thanks,
>> Simon
>> 
> 
> Maybe what you are looking for are the GC.removeRoot or GC.removeRange
> functions which are available in both Phobos and Tango?
> http://www.dsource.org/projects/tango/docs/current/tango.core.Memory.html
> http://www.digitalmars.com/d/2.0/phobos/std_gc.html
> http://www.digitalmars.com/d/1.0/phobos/std_gc.html

You can remove only something previously added.  Since a static array is
not a root nor a range of roots, you can't make it invisible to GC this
way.