DIP66 1.2 (Multiple) alias this. Continuation of work.

[IgorStepanov via Digitalmars-d]

On Monday, 30 March 2015 at 18:33:17 UTC, Andrei Alexandrescu 
wrote:
> On 3/30/15 8:04 AM, Steven Schveighoffer wrote:
>> On 3/29/15 1:34 PM, IgorStepanov wrote:
>>
>>> 1. We should reject types which use opDispatch and alias this 
>>> at the
>>> same time.
>>
>> Why? Alias this has no filter. opDispatch can use template 
>> constraints.
>> It makes perfect sense to prefer opDispatch, unless it doesn't 
>> have a
>> valid match, and then use alias this instead.
>>
>> For example, if I wanted to wrap a type so I can instrument 
>> calls to
>> 'foo', I could do something like this:
>>
>> struct FooWrapper(T)
>> {
>>    T t;
>>    alias t this;
>>    auto opDispatch(string s, A...)(A args) if(s == "foo") {
>> writeln("calling foo"); return t.foo(args); }
>> }
>>
>> Why is this a bad use case?
>
> The idea is to start restrictive and define interaction 
> meaningfully later based on compelling use cases. -- Andrei

Andrei, do you approve those changes? Can we move to work on my 
github PR?