[e-lang] Joe-E Taming Policies

[Mohsen Vakilian]

So, given that ArrayIndexOutOfBoundsException is an honorary interface in
Joe-E, there is no need to suppress its constructors. Right?
How can I overwrite some of the taming policies for my project?

Date: Thu, 17 Sep 2009 21:32:50 -0700
From: Adrian Mettler <amettler at cs.berkeley.edu>
Subject: Re: [e-lang] Joe-E Taming Policies
To: Discussion of E and other capability languages
       <e-lang at mail.eros-os.org>
Message-ID: <4AB30D72.8070600 at cs.berkeley.edu>
Content-Type: text/plain; charset=UTF-8; format=flowed

For the most part, the prohibitions you've encountered are a result of
the taming process being incomplete at present -- there are a lot of
would-be-safe classes that we haven't looked at yet.  We're hoping to
add more on an on-demand basis, so people can build more stuff with it.
  StringBuffer and StringBuilder should both be safe; the only reason
one is currently allowed and not the other is that we have mostly written
single-threaded (or vat-based-concurrency) code, which does not need
StringBuffer's thread-safety.

Hashtable is unsafe to use if you want Joe-E's determinism guarantees to
hold: the iteration order of the hashtable depends on the hash codes
assigned to the objects placed in it; for many classes, the hash code is
nondeterministic as it is the JVM's internal identifier for the object
instance.  Hashtable is OK if you do not need the determinism guarantees.

-Adrian

Mohsen Vakilian wrote:
> Hi,
>
> Can anyone explain the rationale behind the following Joe-E error
> messages? I don't see why the following classes should be disabled by
> Joe-E. For instance, does creating a StringBuffer as a local variable of
> a method cause impurity? Why is StringBuilder allowed but not
StringBuffer?
>
> Disabled constructor from class ArrayIndexOutOfBoundsException called:
> default deny
> Method from disabled type Hashtable called: no policy specified for this
> class
> Disabled constructor from class StringBuffer called: default deny
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