On Tuesday, 25 July 2017 at 15:56:45 UTC, Houdini wrote:
> Yes, but it isn't the default way in C++ to do dynamic instanciation.

https://github.com/isocpp/CppCoreGuidelines this? It's only 2 years old. The new operator predates it by decades.

On Tuesday, 25 July 2017 at 17:16:00 UTC, Kagamin wrote:
> On Tuesday, 25 July 2017 at 15:56:45 UTC, Houdini wrote:
>> Yes, but it isn't the default way in C++ to do dynamic instanciation.
>
> https://github.com/isocpp/CppCoreGuidelines this? It's only 2 years old. The new operator predates it by decades.

I meant :

When you need to instantiate a class, you usually do :

MyClass a;

and not :

MyClass* a = new MyClass();

You're in a value model.

If you find anything in Cpp Guidelines against that, I am interested.

On Monday, 24 July 2017 at 17:42:30 UTC, Steven Schveighoffer wrote:
> 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

It has also the nice property that porting code from Java/C# is actually really easy when using classes as it has more or less the same semantic. When porting code from C and C++ it is often better to use structs.

On 07/26/2017 02:54 AM, Houdini wrote:
> On Tuesday, 25 July 2017 at 17:16:00 UTC, Kagamin wrote:
>> On Tuesday, 25 July 2017 at 15:56:45 UTC, Houdini wrote:
>>> Yes, but it isn't the default way in C++ to do dynamic instanciation.
>>
>> https://github.com/isocpp/CppCoreGuidelines this? It's only 2 years
>> old. The new operator predates it by decades.
>
> I meant :
>
> When you need to instantiate a class, you usually do :
>
> MyClass a;
>
> and not :
>
> MyClass* a = new MyClass();
>
> You're in a value model.

That's my experience as well. However, stack class objects are rare and to repeat Steven, it comes with the problem of slicing. Only after learning D that I realized there were two kinds of C++ types in my code: value types and reference types, latter of which I've achieved with boost::shared_ptr<C>. So, I think D's separation is the right choice.

However, classes are unnecessarily expensive due to that 'monitor' member and carry the mistakes of OOP models adopted by Java, C++, and others. I say this under the influence of open multi-methods[1] and anemic domain models[2].

Ali

[1] http://forum.dlang.org/thread/cigbfrgipbokyetskypk@forum.dlang.org

[2] https://www.meetup.com/D-Lang-Silicon-Valley/events/228027468/