On Fri, Nov 27, 2009 at 02:38:55PM +0100, Martijn Faassen wrote: > I'd ask people to think about this approach without considering > backwards compatibility issues first. Especially given the goal "making > component lookup disappear into the language" makes me think just all > making it calling an interface would be the most elegant approach.
You're convincing.
(I just can't force myself ignore backwards-compatibility issues, I
suppose.)
> So imagining we didn't have to worry about backwards compatibility,
> would you still propose that API, making a difference between adapter
> and utility lookup?
Yes.
> What's the motivation?
The "utilities must be singletons" logic hardcoded in the ZCA.
provideAdapter(factory, adapts=(one, two, three))
provideAdapter(factory, adapts=(one, two))
provideAdapter(factory, adapts=(one, ))
The natural progression, to me, is
provideAdapter(factory, adapts=())
rather than
provideUtility(singleton)
If we decide, ignoring BBB concerns, to make
provideUtility(singleton, provides=IFoo)
be equivalent to
provideAdapter(lambda: singleton, adapts=(), provides=IFoo)
then I'd be very happy to use
IFoo()
for utility lookup.
This also assumes that I'm free to
provideAdapter(arbitrary_callable, adapts=())
and use computed-utility-lookup, or even create utilities on demand in
my arbitrary_callable.
Three cheers for utility and empty-tuple-adapter unification!
> And would you deprecate plain
> adapter calls and prefer 'adapt' all the time?
Ignoring BBB, and assuming utilities-are-just-adapters-on-empty-tuples,
then I'd prefer to use your proposed IFoo(*args, **kw) syntax.
The more I think about it, the more I like this solution.
Ignoring BBB and assuming utilities are distinct fowl, I'd prefer to
have just IFoo.adapt(*args, **kw) and IFoo.utility(**kw).
The phrasing of your question ("deprecate") makes ignoring BBB
impossible, in which case I'd prefer to have a 100% backwards-compatible
IFoo(single_arg, [default]) + IFoo.adapt(*args, **kw) +
IFoo.utility(**kw).
> So as to prevent bikeshedding the API too much, I'm going to take your
> +0.5 anyway. :)
Marius Gedminas
--
http://pov.lt/ -- Zope 3 consulting and development
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