Mixin templates accessing mixed out scope

[anonymous via Digitalmars-d-learn]

On Saturday 12 September 2015 19:36, Prudence wrote:

> On Saturday, 12 September 2015 at 17:11:04 UTC, anonymous wrote:
[...]
>> class MyStore
>> {
>>     class SingleStore
>>     {
>>         static void New() // Removing 'static' compiles
>>         {
>>             new SingleStore();
>>         }
>>     }
>> }
[...]
>> As for a fix: I guess SingleStore isn't supposed to be a nested 
>> class. Mark it static then.
> 
> NO! That is the whole point!

So New is supposed to create a SingleStore that's associated with a MyStore?

That static can't work like that then. It doesn't escape just the first 
level (SingleStore), but all levels (SingleStore and MyStore). That is, a 
static method isn't bound to any object. But you need a MyStore to construct 
a (nested) SingleStore. You have to pass a MyStore somehow.

It can come via `this.outer`:
----
class MyStore
{
    class SingleStore
    {
        SingleStore New()
        {
            return new SingleStore;
        }
    }
}
void main()
{
    auto ms = new MyStore;
    auto ss1 = ms.new SingleStore;
    auto ss2 = ss1.New();
}
----
But here you need a SingleStore object to call New on. Not what you want, I 
think.

Or the MyStore can come via parameter:
----
class MyStore
{
    class SingleStore
    {
        static SingleStore New(MyStore ms)
        {
            return ms.new SingleStore;
        }
    }
}
void main()
{
    auto ms = new MyStore;
    auto ss = MyStore.SingleStore.New(ms);
}
----

Or you can move New a level up, into MyStore, and then plain `this` is the 
needed MyStore:
----
class MyStore
{
    class SingleStore
    {
    }
    SingleStore NewSingleStore()
    {
        return new SingleStore;
    }
}
void main()
{
    auto ms = new MyStore;
    auto ss = ms.NewSingleStore();
}
----