C[omp]ute

From: "andrew cooke" <andrew@...>

Date: Fri, 26 May 2006 18:54:39 -0400 (CLT)

Use a generic static method in the exception class to assert/convert the
type:

  public class TypeException extends Exception {
    public TypeException(String msg) {super(msg);}
    public static <T extends Value> T assertType(Value value, Class<T> clazz)
        throws TypeException {
      if (! clazz.isAssignableFrom(value.getClass())) {
        throw new TypeException("Expected " + clazz.getSimpleName()
                                + ", but got " + value);
      }
      return clazz.cast(value);
    }
  }

Then use as:

  Foo foo = TypeException.assertType(operation(), Foo.class);

Thanks to Phil for pointing out that methods can also be generic.

Andrew