downs Wrote:

> As such, an exception (which is reserved, appropriately, for *exceptional* events), is totally the wrong approach to use.
> 
Yes, function received wrong input, this is normal, if we want, we throw exception, if we want, we ignore it.

> Note that with the current behavior, you can incur the runtime speed loss of throwing an exception if you _want_ to, by using the above templated wrapper, but if throwing an exception were the only possibility, you couldn't possibly get that speed back.
> 
You'll get that speed back without hours spent in debugger trying to figure out, "where this null came from"?

terranium wrote:
> downs Wrote:
> 
> 
>>As such, an exception (which is reserved, appropriately, for *exceptional* events), is totally the wrong approach to use.
>>
> 
> Yes, function received wrong input, this is normal, if we want, we throw exception, if we want, we ignore it.
> 

The point is that offtent a failed cast is not an indecation of an error. For instance code like this

class A {}
class B1 : A {}
class B2 : A {}

void foo(A a)
{
  if(auto b = cast(B1)a) {}
  else if(auto b = cast(B2)a) {}
  else {}
}