escaping addresses of ref parameters - not

[Steven Schveighoffer]

"Andrei Alexandrescu" wrote
> The compiler's escape detection mechanism can't help quite a lot here 
> because the escape hatch is rather indirect.
>
> Initially I thought SafeD should prevent such escapes, whereas D allows 
> them. Now I start thinking the pattern above is dangerous enough to be 
> disallowed in all of D. How about this rule?
>
> ***************
> Rule: ref parameters are PASS-DOWN and RETURN only. No escaping of 
> addresses of ref parameters is allowed. If you want to escape the address 
> of a ref parameter, use a pointer in the first place.
> ***************

As long as there is a way to circumvent this, I'm OK with this rule. 
Something that's the equivalent of a cast.  Two reasons:

1. Using a  * dereference pointer inside a function for all usages is 
sometimes tedious.  This would be a non issue if ref local variables were 
allowed, i.e.:

void foo(int *x)
{
  ref int rx = *x;
  // use rx until you need to copy the address of x.
}

2. you may need to call functions you have no control over that take a 
pointer but do not save a reference to it.  e.g. system calls.

-Steve