Re: Modifying safeScope?

On 22 February 2010 14:35, Kevin Reid <[email protected]> wrote:
> On Feb 22, 2010, at 9:19, Thomas Leonard wrote:
>
>> Another strange thing is that:
>>
>> ? interface SturdyRef {}
>> java.lang.RuntimeException: Failed: can't redefine SturdyRef
>>
>> But I can override it using my loader. I think this is a good thing (I
>> want to run my unit-tests in an environment with fake SturdyRef
>> objects
>> that don't really use the network), but I'm wondering if there's some
>> security reason that means it shouldn't be redefined (auditors, etc)?
>
> This is from the “unshadowable names” auditors plan. The idea was that
> a certain set of nouns (all those in the safeScope) *always* have the
> values they do, so auditors can rely on their behavior.
>
> This system has been superseded by the “guard-based auditing” plan,
> which allows auditors to instead get a certain amount of information
> about what nouns *are* bound to, but E-on-Java has not been updated to
> acknowledge this.

So, should I remove the calls to requireShadowable? It's already
possible to create a scope with whatever bindings you like, e.g.

? e`true`.eval(safeScope.with("true", false))
# value: false

On the other hand, it would be nice to get an error by default if you
try to redefine something because it's probably accidental ("def
shadowing true := false" ?). I think that would be useful even for
names that aren't in safeScope.

Either way, it would also be nice to get an error in this case:

? def foo(x) {
>   def x := 1
>   return x
> }
# value: <foo>

? foo(5)
# value: 1


-- 
Dr Thomas Leonard
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