rtti cast

[Pragma]

terranium Wrote:

> Simon Buerger Wrote:
> 
> > BCS wrote:
> > > this work?
> > > 
> > > if (auto y = cast(A)x)
> > >     y.function_A();
> > > else if(auto y = cast(B)x)
> > >     y.function_B();
> > > 
> > 
> > Well, honestly I'm really impressed. Thats perfectly what I wanted. 
> > Seems to be standard, but I didn't knew about it *lolz*. Okay, seems 
> > to be solved then. Thanks.
> 
> OMG invalid cast doesn't throw exception????

Nope.  Invalid casts simply return null.  If you absolutely need an exception, then you can just wrap the cast in a templated function:

class DynamicCastException : Exception{
	public this(char[] reason){
		super(reason);
	}
}

T dyn_cast(T)(Object x){
    T result = cast(T)x;
    if(result is null) throw new DynamicCastException("Cannot cast to type " ~ T.stringof);
    return result;
}

class A{}

class B:A{}

class C{}

void main(){
	B x = new B();
	C y = dyn_cast!(C)(x);
}