What is the wrong with my C++ interfacing

[Ferhat Kurtulmuş]

On Sunday, 15 March 2020 at 21:16:43 UTC, Arine wrote:
> On Sunday, 15 March 2020 at 20:53:49 UTC, Ferhat Kurtulmuş

> I wouldn't use a class on the D side, unless your C++ type uses 
> virtual functions. Classes in D are different from structs, it 
> is not the same as C++ where they are basically the same thing.

I know their differences, classes are reference types and structs 
are value types in D. I actually don't need this code. I've 
already wrapped many c code, but have no so much experience with 
interfacing C++ code. I am trying to understand capabilities of D 
in interfacing with C++ and its limits. I would like to know why 
I can interface a template-free class, but not a class template.