How do i test that an object is an instance of a particular class in D?

Question

How do i test that an object is an instance of a particular class in D?

Something akin to Javascript's instanceof keyword?

Answer 1

Use cast. It returns a null reference when you attempt to cast to a subclass it isn't an instance of (like C++'s dynamic_cast).

auto a = new Base;
auto b = cast(Child) a;
assert(b is null);

a = new Child;
auto c = cast(Child) a;
assert(c !is null);

Answer 2

typeid expression can tell you if instance is of some exact type (without considering inheritance hierarchy):

class A {}

class B : A {}

void main()
{
        A a = new B();
        // dynamic
        assert( typeid(a) == typeid(B) );
        // static
        assert( typeid(typeof(a)) == typeid(A) );
}