"Joshua 'Schwa' Gargus" schwa@cc.gatech.edu wrote:
Evolving Squeak to meet the requirements for "level 4" security promises to be even more disruptive to the average programmer. On the other hand, it is my belief that this level of security is necessary for Squeak/Croquet to achieve their dream of revolutionizing personal computing.
What does Islands miss in order to be level 4? It allows you to make your own capabilities within the SafeSqueak subset that the Islands compiler runs in by default. As an example, I showed how to do the purses+mints problem, and it was pretty straightforward. Did I miss an email pointing out some hole in my solution?
The annoying part of Islands is the dynamic variables. If you don't trust a capability you are invoking, you have to swap out your island before you invoke it. Likewise, if you are a capability and you don't trust the guy who called you, then you have to swap in a private island during your work.
However, while this swaping code is annoying, it is also straightforward and short. Note that *all* of the dynamic environment gets swapped at once. Thus, while having the dynamic island-wide table of variables is annoying, let it not pass that it transitions Squeak from level 0 to level 4.
This said, there is plenty of room for improvement on Islands. A safe debugger would be great. A way to statically bind to classes would be great. Just please use a different description of the weaknesses of Islands than saying "not level 4". Not only are user-written capabilities available and secure in Islands, but they have been there since early in the project.
As has oft been repeated, the capabilities are the easy part. The hard part is getting the library updated.
Lex Spoon