Re: Implementing typestate

[Freddy via Digitalmars-d]

On Tuesday, 15 September 2015 at 21:44:25 UTC, Freddy wrote:
On Tuesday, 15 September 2015 at 17:45:45 UTC, Freddy wrote:
 Rust style memory management in a library

Wait nevermind about that part, it's harder than I thought.

All hope might not be lost, something like this MIGHT work,but 
i'm am sure I am missing some kind of detail.
---
//doesn't actually compile
struct MutBorrow(T, bool usable_ = true)
{
    private T** ptr;
    enum usable = usable_;
    static if (usable)
    {
        @disable this();
        ref T use()
        {
            return **ptr;
        }
    }
    //...
}

struct Unique(T)
{
    private T* ptr;

    alias user = null;

    ~this()
    {
        static assert(user is null);
        free(ptr);
    }

    auto giveMut(alias local)()
    {
        static assert(is(user : null)));
        user = local;
        local.usable = true;
        local.ptr = &ptr;
    }

    auto takeMut(alias local)()
    {
        static assert(local == user); //is there a proper way to 
compare alias?
        user = null;
        local.usable = false;
    }

    static if ( /+user not null+/ )
    {
        ref T use()
        {
            return *ptr;
        }
    }
}
---