divmod-users team mailing list archive

[Laurens Van Houtven <_@xxxxxx>]

I think I've written the implementation that makes this work.

While powerUp does indeed not work with IPowerupIndirector, inMemoryPowerup
does, and then you can in fact get that thing back from powerupsFor (since
it checks in-memory ones first). I'm not sure if that's a bug, but at least
the current implementation passes the test suite.

Should I fire a merge proposal?


On Thu, Feb 14, 2013 at 11:52 AM, Laurens Van Houtven <_@xxxxxx> wrote:

> Right, I knew powerupsFor with that interface didn't make sense, but
> forgot about __conform__ being called on the pup. Thanks!
>  On Feb 14, 2013 2:05 AM, "Tristan Seligmann" <mithrandi@xxxxxxxxxxxxx>
> wrote:
>
>> On Sat, Feb 9, 2013 at 1:24 PM, Laurens Van Houtven <_@xxxxxx> wrote:
>> >
>> > Why does powerupsFor not have a special case for IPowerupIndirector? is
>> > empowered.powerupsFor(IPowerupIndirector) a valid thing to do? What does
>> > that *mean*?
>>
>> powerupsFor(IPowerupIndirector) is a senseless thing to do, since you
>> cannot install a powerup for IPowerupIndirector (powerUp explicitly
>> disallows this since it won't do anything sensible).
>>
>> When you install a powerup (call it pup) on someItem for
>> ISomeInterface, normally when you retrieve powerups (and the base
>> operation for doing so is powerupsFor) for ISomeInterface, the object
>> pup will be returned as one of the powerups. However, if pup can be
>> adapted to IPowerupIndirector, then the return value of
>> IPowerupIndirector(pup).indirect(ISomeInterface) is returned instead
>> of pup. This is why __conform__ has the special-case it does; if pup
>> is just a regular powerup, pup.__conform__ will be called when Axiom
>> invokes IPowerupIndirector(pup), so we need to avoid trying to do a
>> powerup query for IPowerupIndirector.
>>
>> The only implementation of IPowerupIndirector in Axiom itself is
>> axiom.substore.SubStore; the implementation looks like this:
>>
>>     def indirect(self, interface):
>>         """
>>         Like __conform__, I adapt my store to whatever interface I am
>> asked to
>>         produce a powerup for.  This allows for app stores to be
>> installed as
>>         powerups for their site stores directly, rather than having an
>>         additional item type for each interface that we might wish to
>> adapt to.
>>         """
>>         return interface(self)
>>
>> Hopefully the docstring makes it clear how this is supposed to be used.
>>
>> > I'm considering replacing the implementation of __conform__ with:
>> >
>> > try:
>> >     return self.powerupsFor(interface).next()
>> > except AttributeError:  # self.store == None, self.store.query ->
>> > AttributeError
>> >     return None
>> >
>> > ... modulo the IPowerupIndirector thing, which may have to move to
>> > powerupsFor or may have to be included in that definition.
>>
>> This code seems almost the same as the existing code, except you've
>> removed the special cases for IPowerupIndirector and
>> aggregateInterfaces, and no longer handle the case where there are no
>> powerups for the given interface, so I'm not quite sure what you're
>> trying to accomplish with it.
>> --
>> mithrandi, i Ainil en-Balandor, a faer Ambar
>>
>


-- 
cheers
lvh