Re: Polymorphic recursive class

[Jack Applegame via Digitalmars-d]

On Monday, 13 July 2015 at 13:51:51 UTC, Dmitry Olshansky wrote:

You can do it no problem, it just requires to manually implement boxing and make `right` a template that casts to the right type. The reason is that D doesn't provide an extra abstraction layer that is "auto-magically" there in typical FP language.

Not tested but this should work:

class Nested(T){
        T left;
        void* right_; // or use opaque type if allergic to void*

@property auto right()(){ // empty template to prevent recursion

                return cast(Nested!(T[])right_;
        }

@property auto right(U)(Nested!U type){ // empty template to prevent recursion

                right_ =  cast(void*)right_;
        }
        
        // and lastly the constructor should be templated
        this(U)(T l, Nested!(U) r) {
         left = l;
         right = r;
        }
}

Wow! Template properties is nice idea. Thanks.