passing duck-typed objects and retaining full type information

[Jesse Phillips via Digitalmars-d-learn]

On Tuesday, 11 November 2014 at 19:23:39 UTC, Adam Taylor wrote:
> Now what i want to do is pass some such "container" object to 
> an interface function:
>
> interface MyInterface
> {
> void filterCollisions(S)(S collisionCandidates)
>     if(canRemoveFromContainer!S)
> }

You can't. This is one of the major restrictions of the template 
approach. Generics in C# allow for this, which I believe is 
reliant its JIT compiler.


Once you introduce the need for a vTable (which interfaces do) it 
is no longer possible to require implementation of a "phantom" 
function. Templates don't exist until their use, so it is not 
possible to require an entry in the vTable when the number of 
possible combinations is infinite.