On 04/25/2017 01:20 PM, jmh530 wrote:
> On Monday, 24 April 2017 at 21:59:34 UTC, Atila Neves wrote:
>>
>> Enter the `@Dispose` UDA:
>>
>
> I found this really interesting.
>
> Am I understanding the process correctly: apply map to numbers, allocate
> and return a new array in D, copy it to Excel, call dispose to free the
> D memory.
Yes.
> So if you instead used something like
> scope(exit) Mallocator.instance.dispose(dArg);
> then Excel wouldn't be able to use it because it would be freed by D
> already?
Correct.
> It seems like your @Dispose UDA could have many uses outside of just the
> excel-d package. If I understand correctly, it's similar to C++ smart
> pointers, but not exactly the same. I'm still not sure I totally grok it
> though.
Just by guessing, what we don't see here is that there is a wrapping
layer that does the copying. Disposal logic is called by that layer. So,
your scope(exit) takes place at a higher layer. Here is
made-up-pseudo-code by me. :)
TypeForExcel wrapper_actually_called_by_excel(/* ... */) {
/* ... */
double[] ret_from_your_function = FuncReturnArrayNoGc(/* ... */);
scope (exit) disposal_function(ret_from_your_function);
TypeForExcel arg_to_excel = copy_for_excel(ret_from_your_function);
return arg_to_excel;
}
Ali
