transporting qualifier from parameter to the return value

[Jason House]

Walter Bright Wrote:

> Andrei Alexandrescu wrote:
> > Time has come to make a decision on implementing Steven Schveighoffer's 
> > proposal:
> 
> Unmentioned in the proposal is is inout a type constructor or a storage 
> class? For example,
> 
>      U[inout(T)]* foo(inout(X)*** p) { ... }
> 
> This is much more complex to implement than only allowing inout at the 
> top level, i.e. as a storage class.
> 
> I also prefer the idea of inout on the return type being assumed, rather 
> than explicit:
> 
>      T foo(inout U p) { ... }
> 
> Yes, there's the legacy compatibility issue there. A long time ago, I 
> suggested using the keyword 'return' for that, instead of inout:
> 
>      T foo(return U p) { ... }
> 
> which looks fine until you use it for member functions:
> 
>      T foo() return { ... }
> 
> ugh.


I initially liked return as the keyword as well, but it's problematic for intermediate variables.

inout(U) foo(inout(T) t){
    inout V v = t.someMember.somethingElse;
    return bar(v);
}