• Heromyth (45/45) Oct 14 2018 Here is a sample code
• Basile B. (42/88) Oct 14 2018 The basic problem you're faced to here is that D class /
• Heromyth (63/68) Oct 14 2018 That's a good try. I want to have a try with template mixin.

Heromyth <bitworld qq.com> writes:

Here is a sample code

```d
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);
	// }
}

void main()
{
	ThreadPoolExecutor service = new ThreadPoolExecutor();
	ExecutorService serviceBase = service;
	IExecutorService serviceInterface = service;

	Future!(int) f = service.submit!int(12);
	writeln(f.result);
	
	f = serviceBase.submit!int(12);
	writeln(f.result);

	// f = serviceInterface.submit!int(12);
	// writeln(f.result);
}

```

The **submit** can't be defined in D as done in Java. See also 
(search for exchangeMessageVectorsAsync):

https://www.programcreek.com/java-api-examples/?code=aarmea/noise/noise-master/app/src/main/java/com/alternativeinfrastructures/noise/sync/StreamSync.java

So, is there a better way to do this in D?
Any suggestions are welcome.
Thanks.

Basile B. <b2.temp gmx.com> writes:

On Sunday, 14 October 2018 at 13:21:00 UTC, Heromyth wrote:
 Here is a sample code

 ```d
 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);
 	// }
 }

 void main()
 {
 	ThreadPoolExecutor service = new ThreadPoolExecutor();
 	ExecutorService serviceBase = service;
 	IExecutorService serviceInterface = service;

 	Future!(int) f = service.submit!int(12);
 	writeln(f.result);
 	
 	f = serviceBase.submit!int(12);
 	writeln(f.result);

 	// f = serviceInterface.submit!int(12);
 	// writeln(f.result);
 }

 ```

 The **submit** can't be defined in D as done in Java. See also 
 (search for exchangeMessageVectorsAsync):

 https://www.programcreek.com/java-api-examples/?code=aarmea/noise/noise-master/app/src/main/java/com/alternativeinfrastructures/noise/sync/StreamSync.java

 So, is there a better way to do this in D?
 Any suggestions are welcome.
 Thanks.

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:

import std.stdio;

class Future(T)
{
	T result;

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

interface IExecutorService(Ts...) {
	static foreach(T; Ts)
	 	Future!T submit(T result);
}

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

class ThreadPoolExecutor : ExecutorService!int {
	 override Future!int submit(int result) {
	 	return new Future!int(result + 10);
	 }
}

void main()
{
	ThreadPoolExecutor service = new ThreadPoolExecutor();
	ExecutorService!int serviceBase = service;
	IExecutorService!int serviceInterface = service;

	Future!(int) f = service.submit(12);
	writeln(f.result);

	f = serviceBase.submit(12);
	writeln(f.result);

	f = serviceInterface.submit(12);
	writeln(f.result);
}

so that you can submit and have Future for several types.

Heromyth <bitworld qq.com> writes:

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);
}