alias this

[js.mdnq]

On Friday, 30 November 2012 at 21:46:47 UTC, Rob T wrote:
> On Friday, 30 November 2012 at 14:14:36 UTC, js.mdnq wrote:
>> On Friday, 30 November 2012 at 14:02:42 UTC, Andrej Mitrovic 
>> wrote:
>>> On 11/30/12, js.mdnq <js_adddot+mdng at gmail.com> wrote:
>>>> alias t this;
>>>
>>> This should explain: http://dlang.org/class.html#AliasThis
>>
>> Thanks, I'm sure I saw that at some point but I guess it just 
>> didn't sink in. This seems really cool and might solve a 
>> problem I had much more elegantly...
>
> Note that multiple alias this declarations are slated to be 
> allowed, but have not yet been implemented:
>
> -----------
> Multiple AliasThis are allowed. For implicit conversions and 
> forwarded lookups, all AliasThis declarations are attempted; if 
> more than one AliasThis is eligible, the ambiguity is 
> disallowed by raising an error. Note: Multiple AliasThis is 
> currently unimplemented.
> -----------

I've seen that, how does it work?

struct A{
  Sometype val1;
  int val2;
  alias val1 this;
  alias val2 this; //???
}


How can A act both as Sometype and int? (at least without major 
issues) Does the compiler try to choose the appropriate alias 
depending on the lvalue or rvalue?