Chances of D getting proper runtime reflection?

[Robert Clipsham]

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.

-- 
Robert
http://octarineparrot.com/