escaping addresses of ref parameters - not

[Nick Sabalausky]

"Andrei Alexandrescu" <SeeWebsiteForEmail at erdani.org> wrote in message 
news:gmo8hl$1687$1 at digitalmars.com...
> ***************
> 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.
> ***************
>
> This rule is powerful and leads to an honest style of programming: if you 
> plan on escaping some thing's address, you make that clear in the public 
> signature. The fix to the idiom above is:
>
> struct Widget
> {
>     private Midget * m;
>     ...
>     this(Midget * mdgt) { enforce(mdgt); m = mdgt; ... }
> }
>

Or something like:

struct Widget
{
    private Midget * m;
    ...
    this(NonNullable!(Midget*) mdgt) { m = mdgt; ... }
}

;)

> Widget makeACoolWidget()
> {
>     auto coolMidget = new Midget;
>     return Widget(coolMidget); // works!
> }
>
> Whaddaya think?
>

Sounds reasonable for the most part. My only concern is that (if I'm 
understanding it right) the null-check is moved from compile-time to 
run-time.