/+dub.sdl:

dependency "optional" version="~>0.7.1"

+/

import std.stdio;

​

import optional;

​

void main()

{

    // Safely dispatch to whatever inner type is

    struct A {

        struct Inner {

            int g() { return 7; }

        }

        Inner inner() { return Inner(); }

        int f() { return 4; }

    }

​

    auto d = some(A());

​

    // Dispatch to one of its methods

​

    d.dispatch.f(); // calls a.f, returns some(4)

    d.dispatch.inner.g(); // calls a.inner.g, returns some(7)

​

    // Use on a pointer or reference type as well

    A* e = null;

​

    // If there's no value in the reference type, dispatching works, and produces an optional

    assert(e.dispatch.f() == none);

    assert(e.dispatch.inner.g() == none);

}