Help about Template and class inheritance

[Heromyth]

On Sunday, 14 October 2018 at 15:06:49 UTC, Basile B. wrote:
>
> The basic problem you're faced to here is that D class / 
> interface member functions that are templatized are never 
> virtual. I'm not sure if i understand well the JAVA pattern you 
> try to reproduce but since D interfaces can be templatized you 
> can do something like this, using variadics:
>

That's a good try. I want to have a try with template mixin.

About Java's pattern, see also:
https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/ExecutorService.html


The interface ExecutorService has many implements like 
AbstractExecutorService, ForkJoinPool, 
ScheduledThreadPoolExecutor, ThreadPoolExecutor etc.

The sample above is updated:

import std.stdio;

class Future(T)
{
	T result;

	this(T r) {
		this.result = r;
	}
}

interface IExecutorService {
	// Future!(T) submit(T)(T result);  // can't be implemented
}

abstract class ExecutorService : IExecutorService {
	 Future!(T) submit(T)(T result) {
		return new Future!(T)(result);
	}
}

class ThreadPoolExecutor : ExecutorService {
	// alias submit = ExecutorService.submit;
	
	// override Future!(T) submit(T)(T result) { // can't override it
	// 	return new Future!(T)(result + 10);
	// }
}

class ForkJoinPool : ExecutorService {
	// alias submit = ExecutorService.submit;
	
	// override Future!(T) submit(T)(T result) { // can't override it
	// 	return new Future!(T)(result * 10);
	// }
}

void testBase(ExecutorService service) {

	writeln("testBase: ", typeid(service));
	
	Future!(int) f = service.submit!int(12);
	writeln(f.result);
}

void testInterface(IExecutorService service) {

	writeln("testInterface: ", typeid(service));
	writeln("testInterface: ", typeid(cast(Object)service));
	
	// Future!(int) f = service.submit!int(12);
	// writeln(f.result);
}

void main()
{
	ThreadPoolExecutor threadPool = new ThreadPoolExecutor();
	ForkJoinPool forkJoinPool = new ForkJoinPool();

	testBase(threadPool);
	writeln();
	testBase(forkJoinPool);
	writeln("\n");
	testInterface(threadPool);
	writeln();
	testInterface(forkJoinPool);
}