Re: Registries [2]

Daniel Wallin <[email protected]> writes:

>> > If that is the case, converters need to be added to the local
>> > registry from the outside. So when saying "import converters from
>> > module X" we are really saying "when module X adds a converter to
>> > it's local registry, add it to mine as well".
>>
>>I don't think we have to get that fancy.  We can just
>>initialize module X if it isn't already, and then import all the
>>converters that it has registered.  I'm not too worried about
>>supporting dynamic registration of converters after module
>>initialization time.
>
> Right, or rather; demand that the user initializes module X before.
> This doesn't play well with automatic importing though.
>
>>Hmm, if there was really a mutual dependency we might have an issue,
>>but we could still handle it with a simpler mechanism that simply
>>deferred imports until initialization was completed.
>
> I guess, but it would be nice to handle it without introducing code in
> the dispatch functions. Which is the only place I can think of where
> we could defer importing to.

In Boost.Python, the module initialization function is special; we
actually generate it with a macro and it calls what the user wrote
(for exception-handling purposes), so we can easily generate code
there to handle any deferred imports.

>> > How are extensions to be registered in this central registry? In my
>> > previous post I proposed that they should be registered with a
>> > string literal identifier.
>> >
>> >    register_extension("my_extension");
>> >
>> > How does this fit in with pythons module system? (Note that we are
>> > really registering the extension, and not modules).
>>
>>Every extension is a module (not nececssarily the other way around),
>>so I see no reason not to register the extension by its module name
>
> I guess in python you can ask the interpreter state for the current
> module name?

Erm, I'm not sure you can.  It is supplied as part of the module
initialization function; in fact, it is stored in the module object as
its __name__ attribute, so we can get it thence, assuming we can get
to the module.

> In lua this isn't possible though, so we would need some user defined
> identifier instead.

You've gotta have the module or its name stored somewhere, dontcha?
-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com



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