On Tue, May 22, 2012 at 3:24 PM, Eliot Miranda <eliot.miranda at gmail.com> wrote:

> In part you can use the light-weigth mirror methods in ContextPart, these
> take the object operated on as an argument.  Non-invasive printing could be
> done via execution simulation.  I've already modified the Squeak debugger in
> Qwaq/Teleplace images to use these light-weight mirror primitives so that
> messages are not sent to receivers when simulating execution in the debugger
> (i.e. when doing send instead of step).  If the mirror primitives now work
> on the interpreter I can fold this into trunk.  David, do the mirror
> primitive tests pass on the interpreter?

Yeah, I looked at those, but they seem unnecessary given the existence
of primitive 188, (i.e., CompiledMethod
class>>receiver:withArguments:executeMethod:). With that one primitive
we can do anything we need, with all the logic in the image, instead
of the VM.

Is there some reason you prefer separate primitives for all these
operations? You called them light-weight—what do you mean by that?

> Doing this is also a good idea in general since it allows the debugger to correctly debug proxies also.

Yes!

I guess we have two separate issues here, which I conflated in my
first post. On the one hand, there's non-invasive tool support. That
would be good, and it can be implemented in various ways. Your
debugger changes sound like a good first step in that direction. We
could also implement an inspector based on the light-weight mirror
primitives.

On the other hand, there's the question of a mirror API. That's one of
the things I really like about the Self-Strongtalk-Newspeak-Dart
thread of language design, and hey, it would be great to have that in
Squeak as well. (We stole Morphic from Self, why not mirrors?)

If we did decided to move to a mirror-based API, then non-invasive
mirrors seems like the way to go, and this approach based on prim 188
seems like a good way to implement that. This experiment makes me
think it's feasible. Laying aside the (very real) issues of how to get
from here to there, is this a direction worth exploring, or is
Smalltalk-80-style reflection good enough?

Colin