Creating a pointer/slice to a specific-size buffer? (Handing out a page/frame from a memory manager)

[Gavin Ray]

Suppose that you have a memory manager, or arena-like class, 
which contains a buffer used to store memory.

And you want to hand out chunks of this memory to other parts of 
your program. These chunks should all be `PAGE_SIZE`.


You might have something like:

```d
enum PAGE_SIZE = 4096;
enum BUF_POOL_NUM_PAGES = 1024;

class BufferPool
{
	align(PAGE_SIZE) ubyte[PAGE_SIZE * BUF_POOL_NUM_PAGES] data;

	this()
	{
		mmap(&data, data.sizeof,
                      PROT_READ | PROT_WRITE, MAP_ANONYMOUS | 
MAP_PRIVATE, -1, 0);
	}
}
```

Now there should be a function, like `get_page()`, that returns a 
`PAGE_SIZE` pointer of `ubyte`. But I can only figure out how to 
return a `ubyte[]`:

```d
ubyte[] get_page(frame_idx_t frame_idx)
{
	return data[frame_idx * PAGE_SIZE .. (frame_idx + 1) * 
PAGE_SIZE];
}
```

I am curious if you can return something like `ubyte[PAGE_SIZE]*` 
or `ref ubyte[PAGE_SIZE]`?

Thank you =)