On Thu, Oct 17, 2019 at 11:13 AM Eliot Miranda <eliot.miranda at gmail.com>
wrote:

>
>
> On Wed, Oct 16, 2019 at 2:55 AM Thiede, Christoph <
> Christoph.Thiede at student.hpi.uni-potsdam.de> wrote:
>
>> Hi Marcel,
>>
>> as I see it, this Blocks check only restricts the possible hits, so
>> removing it should not damage any existing functionality. (I am *not*
>> talking about modifying Dangerous!)
>>
>> And if you do
>>
>> MethodFinder methodFor: {{#(1 2). [:x | Smalltalk saveSession.
>> false]}.#()} "pls don't run this!"
>>
>> you will surely expect the side effects to be executed?
>>
>
> If MethodFinder were implemented using simulation (a la Context
> class>>runSimulated:) then we could implement a proper sandbox and
> completely discard Dangerous.  We could catch any attempt to change the
> class hierarchy, save a snapshot, etc.
>

It would be a great project to create a subclass of Context, say
SandboxContext, and have this ensure that when simulating it only creates
more SandboxContexts, never a normal Context, and have SandboxContext
override primitive invocation.  This could be a place to intercept
modification of the class hierarchy (at:put: & become: on MethodDictionary,
and Array to see if an attempt is being made to assign to or become: a
MethodDictionary and/or a subclasses Array).  Perhaps SandboxContext would
need SandboxClosure, perhaps it could simply intercept value: et al on
Closure (see Context>>#doPrimitive:method:receiver:args:).

My gut tells me that while this implementation is clever, it will also be
more general and more easily maintainable than the current one.  There are
issues; a time limit would have to be placed upon simulated executions
(that's also a potential issue for the current implementation).  But it
would be safer since instead of relying on Dangerous to identify dangerous
code it would depend on a reasonably well-defined notion of sandbox, what
is possible to evaluate when searching, and what is not.  One could, for
example, implement an instantiation budget in
SandboxContext>>#doPrimitive:method:receiver:args:.

> Just curious: what would be the block example for these examples?
>>
>> MethodFinder methodFor: {{#(1 2). #even}. #(1)}. *'(data1 reject: data2)
>> '*
>> MethodFinder methodFor: {{#(1 2). #yourself descending}. #(2 1)}. *'(data1
>> sorted: data2) (data1 sort: data2) '*
>>
>> Hey, maybe we should make a small game of it? :-) GuessTheSelectorGame :D
>>
>> Christoph
>>
>>
>> ------------------------------
>> *Von:* Squeak-dev <squeak-dev-bounces at lists.squeakfoundation.org> im
>> Auftrag von Taeumel, Marcel
>> *Gesendet:* Mittwoch, 16. Oktober 2019 10:54 Uhr
>> *An:* gettimothy via Squeak-dev; squeak-dev at mail.squeak.org
>> *Betreff:* Re: [squeak-dev] MethodFinder.Blocks
>>
>> Hi, Christoph.
>>
>> The method finder (or selector browser) has a hard-coded list of possible
>> results (or messages) to not trigger dangerous side effects. Any new
>> feature, such as that "quasi higher-order-message" symbol , would have to
>> be added. Sure. But keep compatiblility with block arguments. :-)
>>
>> Just curious: what would be the block example for these examples?
>>
>> MethodFinder methodFor: {{#(1 2). #even}. #(1)}
>> MethodFinder methodFor: {{#(1 2). #yourself descending}. #(2 1)}.
>>
>> Especially the latter seems kind of cryptic to me.
>>
>> Best,
>> Marcel
>>
>> Am 14.10.2019 01:27:12 schrieb Thiede, Christoph <
>> christoph.thiede at student.hpi.uni-potsdam.de>:
>>
>> Hi all,
>>
>>
>> I just got irritated as I evaluated
>>
>>
>> MethodFinder methodFor: {{#(1 2). #even}. #(1)}
>>
>>
>> and got no hit.
>>
>> This is because the MethodFinder stores an extra list of selector
>> parameters that are assumed to require a block argument (Blocks) -- but
>> nowadays this requirement is not given, as you can pass a Symbol,
>> MessageSend, SortFunction or whatsoever, thanks to polymorphy. So (how) is
>> this block check still relevant? If I remove it, I get the right hit and
>> can do thinks like
>>
>>
>> MethodFinder methodFor: {{#(1 2). #yourself descending}. #(2 1)}.
>>
>>
>> Also, #ifError: will prevent any error thrown if the block does not match
>> the selector.
>>
>>
>> Looking forward to your answers :)
>>
>> Christoph
>>
>>
>>
>
> --
> _,,,^..^,,,_
> best, Eliot
>


-- 
_,,,^..^,,,_
best, Eliot
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