New library: open multi-methods

[jmh530 via Digitalmars-d-announce]

On Tuesday, 18 July 2017 at 16:57:30 UTC, Ali Çehreli wrote:
>
> Perhaps they are all needed but I'm thinking about the need for 
> forward declaration, the need for the underscore prefix, etc.
>

He might be able to at least get rid of the forward declaration 
(not sure on the underscore).

The way it works now is that a class that inherits from an 
interface is not required in any way to implement the methods. 
Suppose he adds another attribute to an interface such that any 
class that inherits from it is required to have methods defined 
for specific functions.

So for instance, the Matrix example might look something like

@trait
interface Matrix
{
   @property int rows() const;
   @property int cols() const;
   @property double at(int i, int j) const;
   @trait void print();
}

I'm not sure this would work because anything that derives from 
Matrix must implement print. However, if it is possible to use 
the attribute to allow the derived classes to ignore print, then 
it might work. Alternately, if there is a way to process the 
interface and tell the compiler to somehow ignore the @trait 
member functions. I don't know if it'll work, but it's an idea.

Anyway, the mixin(registerMethods); could then be adjusted so 
that void print(virtual!Matrix m); is mixed in automatically 
because we now know how to construct it.