System programming in D (Was: The God Language)

[Timon Gehr]

On 01/05/2012 12:26 AM, Manu wrote:
> You just missed a big discussion on IRC about this, where I think I made
> some fair points that people actually agreed with.
>
>     On 1/4/2012 10:53 AM, Manu wrote:
>
>         Oh, and virtual-by-default... completely unacceptable for a
>         systems language.
>           most functions are NOT virtual, and finding the false-virtuals
>         while
>         optimising will be extremely tedious and time consuming.
>
>
>     The only reason to use classes in D is for polymorphic behavior -
>     and that means
>     virtual functions. Even so, a class member function will be called
>     directly if
>     it is private or marked as 'final'.
>
>
> Is this true? Surely the REAL reason to use classes is to allocate using
> the GC?

You can allocate any type using the GC.

> Aren't struct's allocated on the stack, and passed to functions by
> value? Do I need to start using the ref keyword to use GC allocated structs?
>

No.

>     An easy way to find functions that are not overridden (what you
>     called false virtuals) is to add:
>
>        final:
>
>     at the top of your class definition. The compiler will give you
>     errors for any functions that need to be virtual.
>
>     If you don't want polymorphic behavior, use structs instead. Struct
>     member
>     functions are never virtual.
>
>
> I have never written a class in any language where the ratio of virtual
> to non-virtual functions is more than 1:10 or so... requiring that one
> explicitly declared the vastly more common case seems crazy.

Are you sure that is the case?
In my code, most class member functions are true virtual.