Slow performance compared to C++, ideas?

[Max Samukha]

On Wednesday, 5 June 2013 at 22:03:05 UTC, Walter Bright wrote:

> We can do an upgrade path as follows:
>
> 1. Introduce 'virtual' storage class. 'virtual' not only means 
> a method is virtual, but it is an *introducing* virtual, i.e. 
> it starts a new vtbl[] entry even if there's a virtual of the 
> same name in the base classes. This means that functions marked 
> 'virtual' do not override functions marked 'virtual'.

Note that 'new' modifier in C# is applicable not only to virtual 
methods (MS calls it "name hiding"). Not using 'new' when hiding 
a public member is a warning.

References:
http://msdn.microsoft.com/en-us/library/vstudio/435f1dw2.aspx
http://msdn.microsoft.com/en-us/library/aa691135(v=vs.71).aspx
http://msdn.microsoft.com/en-us/library/aa645767(v=vs.71).aspx

Some points from limited personal experience:

1. Private final methods in D can hide base methods. That's 
*useful*. Don't try to change that.
2. Public final methods in D cannot be hidden. That's been a 
problem for me and other people.
3. I've seen 'new' on final methods in C# in practice and used it 
myself. I've never seen virtual methods being hidden and never 
needed that myself.

>
> 2. Issue a warning if a function overrides a function that is 
> not marked 'virtual'.
>
> 3. Deprecate (2).
>
> 4. Error (2), and make non-virtual the default.