[z-machine] Different 1.1 proposal: put_prop and get_prop

[David Kinder]

> Absolutely.  But it presumably might be a good idea to change the spec
> so that any terp meeting it would successfully play existing games.
> Within that, it would be good for people developing new games to know
> whether there will be portability problems on other terps.

Agreed.

> That would make sense, if you make that *definitely* printing a
> diagnostic message - most of the other illegal uses in the spec are
> required to print a message *and halt*.  As for @get_prop, this
> behaviour would at least alert the programmer to the fact that they
> have a problem with a two-or-more-word property.

Thinking specifically about Frotz, I was thinking of another of the
messages that show up when things like vile zero errors occur. These
can be suppressed by the user.

> I wonder if Ben found out whether Christminster was expecting the
> first two bytes of data, or something else?  I'd bet it was the
> former.

>From Ben's message: "It's looking to see if a certain property exists
on the object, and so doesn't care about the value returned as long as
it's non-zero." So a definition that it returns the length would keep
Christminster happy.

David