Chances of D getting proper runtime reflection?

[Jacob Carlborg]

On 2011-08-21 13:42, Robert Clipsham wrote:
> On 21/08/2011 11:55, Jacob Carlborg wrote:
>> What are the chances of D getting proper runtime reflection? Something
>> like this:
>>
>> class Foo
>> {
>> private int a;
>>
>> private void bar (int i)
>> {
>> a = i;
>> }
>> }
>>
>> auto foo = new Foo;
>> Object o = foo;
>> o.setInstanceVariable("a", 3);
>> assert(foo.a == 3);
>>
>> This would be useful as well:
>>
>> o.send("bar", 5);
>> assert(foo.a == 5);
>> assert(foo.a == o.getInstanceVariable("a"));
>>
>> Currently I have most use of the first example. These example should
>> work regardless if the fields/methods are private, protected or public.
>>
>> As far as I know this wouldn't require any changes to the language, only
>> the compiler and runtime would need to be modified. To me, it doesn't
>> look that complicated to implement, the runtime just needs to store an
>> associative arrays that maps names of instance variables and methods to
>> their addresses. This could probably be stored in the ClassInfo.
>> Something like this:
>>
>> Foo.classinfo.setInstanceVariable(foo, "a", 3);
>>
>> And this could be shorted to:
>>
>> o.setInstanceVariable("a", 3);
>>
>> "setInstanceVariable" could just forward the call to the class info.
>>
>
> You can actually do all of this now (albeit using a mixin), there's just
> no standard way of doing it. All you need to do is use compile time
> reflection to pull out all the fields/methods then store them for use at
> runtime. It would be good to get this functionality into phobos so
> there's a standard way of doing it though. The plus side to having to
> use a mixin is you don't get loads of bloat from classes you never want
> to reflect at runtime.

Yes, I know. But the point is to be able to do it without the use of 
mixins. It needs to work with third party types, otherwise there no use. 
It also needs to work when the static type is Object.

You're already paying for the class info, which already contains 
getMembers. But this methods always returns an empty array and as far as 
I can see, it's not possible to set/get fields or call methods via these 
member instances.

-- 
/Jacob Carlborg