[plt-scheme] GC and scheme C API

> If `eptr' never refers to a GCable value, then don't refer to it in the
> mark or fixup function. Ignore it, the same as an integer value.

Yes eptr does not refer to GCable value.
Thanks , for clearing doubt.


On Mon, May 31, 2010 at 8:31 PM, Matthew Flatt <mflatt at cs.utah.edu> wrote:
> At Mon, 31 May 2010 20:26:56 +0530, Veer wrote:
>> Suppose i get external pointer (not scheme pointer) , and other
>> function calls make use
>> of this pointer .
>>
>> So , what i do is make a new scheme type "<eobject>" and structure like this:
>>
>> typedef struct {
>>   Scheme_Object sob;
>>   External_Object* eptr;
>> }EObject;
>>
>> and use  "scheme_malloc_tagged" ,
>> GC_register_traversers(etype,e_size,e_mark,e_fixup, ....)
>> and "scheme_register_finalizer" to complete the construction of
>> EObject , and return it as Scheme_Object*
>>
>> Is it correct to assume that :
>> --  e_mark is used to tell what other pointers are in the EObject
>> --  e_fixup is used to fix the marked pointers  in EObject , so that
>> they can point to correct objects.
>> --  finalizer func can be used to free eptr in EObject , when there
>> are no reference to EObject in scheme
>>
>> Since eptr is not a scheme_pointer , what role does it have in e_mark
>> and e_fixup ?
>
> If `eptr' never refers to a GCable value, then don't refer to it in the
> mark or fixup function. Ignore it, the same as an integer value.
>
>