Cannot dup an associative array but why?

[Jean-Louis Leroy via Digitalmars-d-learn]

On Tuesday, 11 July 2017 at 17:20:33 UTC, Ali Çehreli wrote:

> That's some serious code you've written there and you must be 
> happy that 'virtual' is not a keyword in D. ;)

Thanks. Haha I would have used virtual_ like I did in C++ ;-)

> Maybe others can come up with ideas on a better syntax.

When it is presentable (I'm almost there) I plan to ask a review. 
I would welcome suggestions about the syntax - which is not too 
bad as it is now, I have been happily surprised with what is 
feasible. It even supports overloading methods.

The thing that annoys me most is having to pass a string to 
'method'. And attributes are not allowed on arguments. I wish I 
would make something like this work:

     mixin method!(fight, string, virtual!Character, 
virtual!Creature, virtual!Device);

     // or:
     mixin method!(fight, string, @virtual Character, @virtual 
Creature, @virtual Device);

     // even better
     mixin method!(fight, function string(@virtual Character, 
@virtual Creature, @virtual Device));

     // and if there is a catch-all implementation:
     mixin method!(fight, function string(@virtual Character, 
@virtual Creature, @virtual Device) {
         // body
     }

I tried to get inspiration from Yes and No, considered using 
opDispatch, but I haven't found a way yet.

> Just to get the conversation going and without thinking it 
> through, how about something like the following?
>
> struct Virtual(Args...) {
>     // ...
> }
>
> @Virtual("t", "d", "w")
> string fight(Character t, Dragon d, Hands w) {
>     return "you just killed a dragon with your bare hands. 
> Incredible isn't it?";
> }

The 'virtual' qualifier applies to the arguments in the method 
declaration, not the specializations. Also, I prefer to keep the 
qualifiers stuck to the argument. It's clearer. Interesting idea 
though.

> Then, something like the following which would parse the module 
> to do its magic:
>
> mixin ProcessMethods();

Very interesting. I don't like the repetition of 'mixin' in front 
of each 'method' and 'implementation'.

Hmmm...if ProcessMethods() can find @Virtual(...) functions can't 
it find functions that have virtual! parameters?