Re: E patches for review: ELoader, FileGetter

On 24 May 2010 17:57, Kevin Reid <kpreid-M/[email protected]> wrote:
> On May 24, 2010, at 11:10, Thomas Leonard wrote:
>> On Mon, 2010-05-24 at 09:51 -0400, Kevin Reid wrote:
[...]
>>>I just think that the *default* module-loading protocol
>>> should permit modules to instantiate shared DeepFrozen objects.
>>
>> I can think of cases where that would be useful (e.g. interfaces and
>> guards). I assume such changes would also apply to the regular
>> ImportLoader (i.e. they're not specific to the modules system)?
>
> We want a module system that replaces ImportLoader.
>
>> What about these though?
>>
>> # A.emaker
>> interface foo {}
>> def x := 0
>> [x, foo]      # (DeepFrozen)
>>
>> # B.emaker
>> interface bar {}
>> var x := 0
>> [x, bar]      # (not DeepFrozen)
>>
>> Will I get a single instance of "foo" each time I import A, but a
>> different (!=) instance of "bar"?
>
> As it currently stands, if it were not for the fact that foo and bar
> are not actually DeepFrozen, the answer is yes.

[ actually, not since r753 ]

> I think the right answer here is that all elements of a module
> (<someloader:B>) should be evaluated at-most-once and required to be
> DeepFrozen, unless explicitly specified to act otherwise (either in
> metadata or metacode).

OK, if we're changing it everywhere so it's consistent then I think
I'm happy with that. It would be more like the way I expected E to
work when I first started using it. It would simplify some of my code,
too.

What are the security implications? e.g. say I have a file like this:

# securePair.emaker
interface FooGuard guards FooAuditor { }
[FooGuard,FooAuditor]

Before, another emaker could import this and use FooAuditor. If anyone
else imported it, they just got a new copy and no harm done. Now, that
same code would be insecure.

I don't think I've seen any code like this, but maybe there are more
subtle cases?


-- 
Dr Thomas Leonard		ROX desktop / Zero Install
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