How to get the pointer of "this" ?

[Vinod K Chandran]

On Tuesday, 26 May 2020 at 13:37:22 UTC, Vinod K Chandran wrote:
> On Tuesday, 26 May 2020 at 12:41:20 UTC, John Chapman wrote:
>> On Monday, 25 May 2020 at 16:26:31 UTC, Vinod K Chandran wrote:
>>> Here is my full code. Please take a look.
>>> https://pastebin.com/av3nrvtT
>>
>> Change line 124 to:
>>
>> SetWindowSubclass(this.mHandle, SUBCLASSPROC(&btnWndProc), 
>> UINT_PTR(subClsID), cast(DWORD_PTR)cast(void*)this);
>>
>> That is, change `&this` to `cast(void*)this`.
>
> Hi,
> Thanks for the reply. That will work like charm but we need to 
> change the code in subclassed button's WndProc  like this--
> extern(Windows)
> private LRESULT btnWndProc(HWND hWnd, UINT message, WPARAM 
> wParam, LPARAM lParam, UINT_PTR scID, DWORD_PTR refData) {
>     try  {
>
>         Button thisBtn = cast(Button)cast(void*)refData;
>      {
>     catch (Exception e) {}
>     ....

So far now, two solutions are very clear for this problem.
1. As per John Chapman's suggestion - use 
cast(DWORD_PTR)cast(void*)this).
2. Use another varibale to use as an lvalue. -
      Button dummyBtn = this;
      cast(DWORD_PTR)&dummyBtn;
Among these two, i think 2nd option is good. Am i right ?