[level]

the .ice file is

class base
{
int d;
};
class stringbase extends base
{
string s;
};
class Hello
{
nonmutating void sayHello(base i);
idempotent void shutdown();
};
....

In the implement file , in the function

void sayHello(base i);
How can I dynamic_cast or static_cast the base pointer to stringbase pointer?