Deprecations for 3.0

[Andrew Whitworth]

On Fri, Sep 17, 2010 at 11:18 AM, Peter Lobsinger <plobsing at gmail.com> wrote:
> But more to the point, they are insufficient for handling aggregates.
> If a PMC cointaining ATTR isn't a simple PMC*, but something more
> complicated (like PMC**), the whole thing falls appart. Clearly you
> can still have one PMC reference another by these means, but the
> SET_ATTR and GET_ATTR macros cannot express these assignments.

Ah, I see where my problem is. Parrot used to have real write-barrier
macros GC_WRITE_BARRIER() and similar things. I see now that those
macros do not appear to be present anymore. I agree with you that
SET_ATTR and GET_ATTR macros are not sufficient for this purpose. We
previously did have (and will likely have again) better macros which
will be sufficient.

If we need to add a deprecation note for adding new macros, we can do that.