launchpad-dev team mailing list archive

[Aaron Bentley <aaron@xxxxxxxxxxxxx>]

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On 07/26/2010 12:13 PM, Julian Edwards wrote:
> On Monday 26 July 2010 16:24:33 Aaron Bentley wrote:
>> On 07/26/2010 11:10 AM, Julian Edwards wrote:
>>> On Monday 26 July 2010 16:01:31 Jonathan Lange wrote:
>>>>> I guess I'm struggling to see how @classmethod is useful then.  In
>>>>> fact, it's dangerous.
>>>>
>>>> Why do you think it's dangerous?
>>>
>>> Because it allows someone to get hold of a new object that is not
>>> security wrapped.
>>
>> So does FooSet.new.  What's the difference?  
> 
> None - that's exactly what I was referring to.

So this means that FooSet.new is also dangerous.  So why do you say that
a @classmethod is dangerous, if it's no more dangerous than a normal method?

>>>  I don't know why you'd ever want to do that.
>>
>> It's very convenient in test code.
> 
> Why?  Why do you need to ignore security?

Because I want to set up preconditions for my test that are much easier
to do by poking at internal state than by using the approved Interface.
 Because it's sometimes easier or more precise to verify postconditions
by looking at internal state than by using the approved Interface.

> If it is *really* needed, I would *much* rather see an explicit 
> removeSecurityProxy() with a comment explaining why you need to remove the 
> wrapper.

Sure, explicitly removing the security proxy is clearer.  I don't agree
about the need for a comment.

>> def FooSet.destroyFoo(self, foo) <- We can't check whether the user has
>> permission to delete this object at the zope level, because it's foo,
>> not self.
> 
> I agree with all of this, except that I can't say I've ever been encouraged to 
> have a delete method on a utility :)

Having seen a delete method on a utility, I can only assume some people
have been.

> But still, we can do store.remove() anywhere and that's not checked.

Indeed.  It's not about making evil impossible, it's about helping
ourselves to avoid mistakes.

Aaron
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