Why structs and classes instanciations are made differently ?

[Steven Schveighoffer via Digitalmars-d-learn]

On 7/24/17 11:45 AM, Houdini wrote:
> On Monday, 24 July 2017 at 15:41:33 UTC, Steven Schveighoffer wrote:
> 
>> Because types with inheritance generally don't work right if you pass 
>> by value (i.e. the slicing problem).
>>
>> structs don't support inheritance or virtual functions, so they can be 
>> safely passed by value.
> 
> But in C++, we pass them by reference also to avoid copies (const &).
> The potential polymorphic usage is not the only point to consider.
> 

In C++ class and struct are pretty much interchangeable, so technically, 
class is a wasted keyword for default visibility.

In D, I would use classes for any time I need polymorphism, and use 
structs otherwise.

-Steve