Adding the ?. null verification

[Tobias Pankrath via Digitalmars-d]

>
> In this case, the signature constraint on opDispatch could be 
> used for
> auto completion:
>
>             auto opDispatch(string field)()
>                 if (is(typeof(__traits(getMember, t, field))))
> 		...
>
>>From the signature constraint, it should be obvious that 
>>"field" must be
> among the members of t.
>
> Of course, checking signature constraints isn't always 
> practical in the
> general case where it may be arbitrarily complex, but obvious 
> cases like
> this one should be easily manageable, no?
>
In this case auto completion could work flawless because of

alias this t;

At least for cases where even a frontend based tool has a hard 
time, we could introduce a ddoc section for this, if there really 
is a need.

/**
  * Dispatch method call.
  * Completion: LIKE t
  */
auto opDispatch(string field)() { ... }

If phobos does this consistently the tools will recognize this.