Get calling this, if exists

[Mike Parker via Digitalmars-d-learn]

On Friday, 24 June 2016 at 02:57:28 UTC, "Smoke" Adams wrote:
> Is there a type of __THIS__ construct similar to __FILE__ and 
> __LINE__?
>
> Something that returns the current this ptr if it exists, null 
> otherwise.
>
> Log(string filename = __FILE__, Object obj = __THIS__)()
> {
>    // inspect obj and do stuff
> }

There is no 'this' pointer unless you are calling a member 
function on an aggregate, so you can never have one that is null.