Inner classes - More expressiveness needed

[Steven Schveighoffer]

"Janice Caron" wrote
> On 10/25/07, Steven Schveighoffer <schveiguy at yahoo.com> wrote:
>> And what would you have the outer member point to? :)  It needs to point 
>> to
>> an instance of the outer class, and if you have a static function, there 
>> is
>> no instance of an inner or outer class.
>>
>> If you need a function that requires an instance of the outer class, but 
>> not
>> an instance of the inner class, the function belongs in the outer class. 
>> I
>> think that is what you wanted?
>
> Hmm... How to explain...?
>
> OK, to start with, I had a class which looked something like this:
>
>    class B
>    {
>        int n;
>        private this(int n) { this.n = n; }
>        static B opCall(int n) { return new B(n); }
>        int f() { return 0; }
>    }
>
>    B B_Factory(int n)  { return new B(n); }
>
>    // In another file
>    auto b = B(42);
>    int n = b.f;
>
> This all worked very nicely. But then I decided to make B an inner
> class, so naturally I tried just wrapping it in class A {}, to give
>
>    class A
>    {
>        int m;
>
>        class B
>        {
>            int n;
>            private this(int n) { this.n = n; }
>            static B opCall(int n) { return new B(n); }
>            int f() { return m; }
>        }
>
>        B B_Factory(int n)  { return new B(n); }
>    }
>
>    // In another file
>    auto a = new A;
>    auto b = a.B(42);
>    int n = b.f;
>
> and this is the point at which it stopped compiling.
>
> I guess maybe it was a dumb thing to do, using static opCall and
> making the constructor private. The thing is, while the static opCall
> does not compile, the standalone function B_factory() is perfectly OK
> and compiles just fine. That's because B_Factory is considered to be a
> member function of A, wheras A.B.opCall() isn't.

Yeah, I see your point.  I don't think there's a way to name the function 
a.B() without having a static opCall, which isn't what you want.  So I guess 
B_Factory will have to do :)

-Steve