I have the following MWE:

import std.exception;
import std.stdio;

abstract class B
{
   B opCall() {
      throw new Exception("NotImplemented");
   }
}

class A : B
{
   override B opCall() {
      return new A();
   }
}

int main() {
   B a = new A();
   a();
   readln();
   return 0;
}

But B.opCall() gets called! I thought polymorphism was cool until now....

How can I get this to work the way I expected it to? Would an abstract method in base do it?

On Sunday, 4 September 2022 at 17:36:24 UTC, Enjoys Math wrote:

import std.exception;
import std.stdio;

abstract class B
{
   B opCall() {
      throw new Exception("NotImplemented");
   }
}

class A : B
{
   override B opCall() {
      return new A();
   }
}

int main() {
   B a = new A();
   a();
   readln();
   return 0;
}

Okay... now the MWE works as I expected polymorphism to work, but my complicated library is not doing it right...

:\

On Sunday, 4 September 2022 at 17:38:54 UTC, Enjoys Math wrote:

import std.exception;
import std.stdio;

abstract class B
{
   B opCall() {
      throw new Exception("NotImplemented");
   }
}

class A : B
{
   override B opCall() {
      return new A();
   }
}

int main() {
   B a = new A();
   a();
   readln();
   return 0;
}

Here is a link to the library on github. Please help me solve this!! :D

https://github.com/enjoysmath/diagram-chaser

On Sunday, 4 September 2022 at 17:43:33 UTC, Enjoys Math wrote:

import std.exception;
import std.stdio;

abstract class B
{
   B opCall() {
      throw new Exception("NotImplemented");
   }
}

class A : B
{
   override B opCall() {
      return new A();
   }
}

int main() {
   B a = new A();
   a();
   readln();
   return 0;
}

Simply git clone it and run from main.d or hit debug in VisualD to see my problem. It's calling the base class method which throws a NotImplemented exception, but it should be calling one of the derived subclasses. I will keep coding on it and update the code, but if I get it fixed, I'll post an update here.

On Sunday, 4 September 2022 at 17:50:10 UTC, Enjoys Math wrote:

Fixed. I was simply not implementing anything in the subclass.