[Zope3-dev] Re: ObjectHub

[Gary Poster]

Steve Alexander wrote:
> Can you explain what you want in terms of the Requirements for the 
> 'register' method that I posted?
> 
> Here they are again:
> 
> * Postcondition: the given object's location is registered
> 
> * If the postcondition cannot be met, you get an exception
> 
>   Otherwise...
> 
> * You want to know the hubid of the registration
> 
> * You want to know whether registration did any work
> 
> I'd like to start by finding out if the requirements for this method are 
> reasonable. Then, we can move on to think about how we spell it.

Sure.  I think the first three are great.  The last one feels somewhat 
questionable to me, but then you gave a use-case in your code, so ok, I 
guess.  If you didn't have the last requirement, of course, you could 
always just return the hubid:

 >>> hub.register('/foo/bar/baz')
23
 >>> hub.register('/foo/bar/baz')
23

Is the use case you gave for requirement 4 a reasonable one?  My 
response is, again, +0.
I see it, but grudgingly: I want to say YAGNI.

>>  > There's a similar issue with 'unregister': it raises a 
>> NotFoundError if
>>  > the object/location is not registered.
>>  >
>>  > We can change 'unregister' to return a bool. This is fine, as it
>>  > currently does not return anything meaningful.
>>
>> +.5: if the change above is implemented,, +1, and if not, -0.
> 
> 
> I'm drawing on experience from the Zope2 ZCatalog here: raising an 
> exception for unregistering an object twice isn't all that helpful. The 
> second unregistration isn't harmful. If you want to log this as an 
> warning, the application method that calls 'unregister' can do that.

Agreed, and thus the full +1 in the first case.  All I want is 
reasonably parallel behavior between register and unregister: I don't 
want one to raise an error and the other to not raise an error.

Gary