Re: [Zope-dev] split out zope.component mechanics into a separate package (was Re: improving the utility and adapter lookup APIs)
Chris McDonough wrote: [snip] It tries to address the following problem. Currently people seem to get wrapped around the axle and confused by the purpose of the ZCA, which currently implies at least two different things: - Machinery to perform complex registrations and lookups using interfaces in the form of a registry. - A global API that presents a view of the world: there are these things called utilities and adapters, and this API is how you do adaptation and utility lookup. These two things are conceptually distinct. It shouldn't be necessary to need to understand the concept of utility and adapter to use a registry. A registry is just machinery that uses interfaces as registration markers for the benefit of later arbitrary lookups, not necessarily just for finding utilities or finding and calling adapter factories. For instance, you might use the registry to register some callable that accepts *no* arguments with, say, two requires arguments. You shouldn't need to call this an adapter, because it's not one; you just want to register something and get it back when you ask nicely. Agreed, but isn't this registry in zope.interface already? I mean zope.interface.adapter.AdapterRegistry? I've used this for the not-really-adapting-as-I-don't-want-to-call in a library of mine recently (traject). You factored out the registry functionality, but there are still plenty of references to utilities in it, for instance. As far as I understand it that would be putting too much into zope.registry already? The API of a registry should be able to evolve separately from the API of its consumers (the global ZCA API is only one consumer). The current registry API permits the concepts of utility and adapter to bleed into the implementation, but this needn't be the case forever. We could provide (and document) a very simple registry base class with a normalized API that didn't have any of this conceptual baggage; it would be extremely popular, I think. Likewise, it should be possible to use a different registry implementation to service the ZCA global API. This is possible right now via getSiteManager.sethook, of course. You factored various related things together - perhaps it would make sense to do this refactoring within zope.component? I'm +1 on making zope.event part of zope.component and deprecating zope.event. Speculating, would it instead make sense to move zope.registry functionality into zope.interface? The only additional dependency is zope.event. At first glance the answer would be no as it really introduces various component architecture concepts... It might make sense to me to put a very simple component registry in zope.interface: it already has the concept of adapter baked in. Yeah, I think this makes more sense. So, we have a number of projects: * interface API - the stuff around calling interface I sketched out elsewhere. I think this is relatively low-hanging fruit. On the other hand it breaks backwards compatibility. I wouldn't want this project to depend on the other improvements, and I don't think it has to, so I'd like to see this as zope.component 4.0. * improving and move code that's general enough from zope.component into zope.interface. What this would look like I'm not quite sure about yet, as zope.registry at first glance contains a lot of knowledge about utilities and such still. There are backwards compatibility issues surrounding persistence but hopefully less around the APIs themselves. * an improved registration API for zope.component. This would affect a lot of code that does registration. Documentation projects should go along with all of those. Regards, Martijn ___ Zope-Dev maillist - Zope-Dev@zope.org https://mail.zope.org/mailman/listinfo/zope-dev ** No cross posts or HTML encoding! ** (Related lists - https://mail.zope.org/mailman/listinfo/zope-announce https://mail.zope.org/mailman/listinfo/zope )
Re: [Zope-dev] split out zope.component mechanics into a separate package (was Re: improving the utility and adapter lookup APIs)
Chris McDonough wrote: Chris McDonough wrote: If some set of ZCA APIs made it the responsibility of the *caller* to invoke the adapter with arguments would go a long way between normalizing the difference between utilities and adapters (because they would essentially then be the same thing). The very core mechanics of how a component registry behaves resides almost entirely in the zope.component.registry module. It would be useful to split these core mechanics into a separate package. Here's why: - The zope.component module carries along an expectation of a particular global API. This global API is not required to use the mechanics of the underlying registry machinery. - The zope.component package has a number of features that are irrelevant to the operation of the core registry itself, such as persistence and security. - The registry itself is useful outside the context of the zope.component API package; the API is essentially just candy on top of the registry itself. I have created such a package at http://svn.zope.org/Sandbox/chrism/zope.registry It contains an implementation of the registry and the tests for the registry object. It depends on zope.interface and zope.event. I'd like to actually remove the zope.event dependency and release a newer version of zope.event that uses a global inside zope.registry as the list of registered object (reverse the dependency). After that's done, I'd suggest we make zope.component depend on zope.registry. At this point, people can innovate with their own APIs to the registry object as necessary; they needn't carry along the baggage of the expecation of the older zope.component API working in their app. One of my first responses would be some worry about zope.component growing a *new* dependency. The goal of zope.component is that it's one of those packages with only a few... I'm trying to see who would be using zope.registry for what exactly. Would it be much harder to experiment with these new APIs on top of zope.component? You'll get a bit more baggage, but the minimal dependency story should be quite small already. I'd rather get some of the additional dependencies (that have a lot to do with supporting ZCML) out of it, instead of moving its core functionality out. You factored various related things together - perhaps it would make sense to do this refactoring within zope.component? I'm +1 on making zope.event part of zope.component and deprecating zope.event. Speculating, would it instead make sense to move zope.registry functionality into zope.interface? The only additional dependency is zope.event. At first glance the answer would be no as it really introduces various component architecture concepts... Regards, Martijn ___ Zope-Dev maillist - Zope-Dev@zope.org https://mail.zope.org/mailman/listinfo/zope-dev ** No cross posts or HTML encoding! ** (Related lists - https://mail.zope.org/mailman/listinfo/zope-announce https://mail.zope.org/mailman/listinfo/zope )
Re: [Zope-dev] split out zope.component mechanics into a separate package (was Re: improving the utility and adapter lookup APIs)
Martijn Faassen wrote: Chris McDonough wrote: Chris McDonough wrote: If some set of ZCA APIs made it the responsibility of the *caller* to invoke the adapter with arguments would go a long way between normalizing the difference between utilities and adapters (because they would essentially then be the same thing). The very core mechanics of how a component registry behaves resides almost entirely in the zope.component.registry module. It would be useful to split these core mechanics into a separate package. Here's why: - The zope.component module carries along an expectation of a particular global API. This global API is not required to use the mechanics of the underlying registry machinery. - The zope.component package has a number of features that are irrelevant to the operation of the core registry itself, such as persistence and security. - The registry itself is useful outside the context of the zope.component API package; the API is essentially just candy on top of the registry itself. I have created such a package at http://svn.zope.org/Sandbox/chrism/zope.registry It contains an implementation of the registry and the tests for the registry object. It depends on zope.interface and zope.event. I'd like to actually remove the zope.event dependency and release a newer version of zope.event that uses a global inside zope.registry as the list of registered object (reverse the dependency). After that's done, I'd suggest we make zope.component depend on zope.registry. At this point, people can innovate with their own APIs to the registry object as necessary; they needn't carry along the baggage of the expecation of the older zope.component API working in their app. One of my first responses would be some worry about zope.component growing a *new* dependency. The goal of zope.component is that it's one of those packages with only a few... I'm trying to see who would be using zope.registry for what exactly. Would it be much harder to experiment with these new APIs on top of zope.component? You'll get a bit more baggage, but the minimal dependency story should be quite small already. I'd rather get some of the additional dependencies (that have a lot to do with supporting ZCML) out of it, instead of moving its core functionality out. I guess this was just a way of trying to draw a line between the component architecture (and the conceptual baggage which surrounds it) and useful machinery that currently is hidden inside of it that really should have a life of its own. It's obviously not the only way to do that. It tries to address the following problem. Currently people seem to get wrapped around the axle and confused by the purpose of the ZCA, which currently implies at least two different things: - Machinery to perform complex registrations and lookups using interfaces in the form of a registry. - A global API that presents a view of the world: there are these things called utilities and adapters, and this API is how you do adaptation and utility lookup. These two things are conceptually distinct. It shouldn't be necessary to need to understand the concept of utility and adapter to use a registry. A registry is just machinery that uses interfaces as registration markers for the benefit of later arbitrary lookups, not necessarily just for finding utilities or finding and calling adapter factories. For instance, you might use the registry to register some callable that accepts *no* arguments with, say, two requires arguments. You shouldn't need to call this an adapter, because it's not one; you just want to register something and get it back when you ask nicely. The API of a registry should be able to evolve separately from the API of its consumers (the global ZCA API is only one consumer). The current registry API permits the concepts of utility and adapter to bleed into the implementation, but this needn't be the case forever. We could provide (and document) a very simple registry base class with a normalized API that didn't have any of this conceptual baggage; it would be extremely popular, I think. Likewise, it should be possible to use a different registry implementation to service the ZCA global API. This is possible right now via getSiteManager.sethook, of course. You factored various related things together - perhaps it would make sense to do this refactoring within zope.component? I'm +1 on making zope.event part of zope.component and deprecating zope.event. Speculating, would it instead make sense to move zope.registry functionality into zope.interface? The only additional dependency is zope.event. At first glance the answer would be no as it really introduces various component architecture concepts... It might make sense to me to put a very simple component registry in zope.interface: it already has the concept of adapter baked in.
Re: [Zope-dev] split out zope.component mechanics into a separate package (was Re: improving the utility and adapter lookup APIs)
On Nov 25, 2009, at 5:08 PM, Chris McDonough wrote: Chris McDonough wrote: If some set of ZCA APIs made it the responsibility of the *caller* to invoke the adapter with arguments would go a long way between normalizing the difference between utilities and adapters (because they would essentially then be the same thing). The very core mechanics of how a component registry behaves resides almost entirely in the zope.component.registry module. It would be useful to split these core mechanics into a separate package. Here's why: - The zope.component module carries along an expectation of a particular global API. This global API is not required to use the mechanics of the underlying registry machinery. - The zope.component package has a number of features that are irrelevant to the operation of the core registry itself, such as persistence and security. - The registry itself is useful outside the context of the zope.component API package; the API is essentially just candy on top of the registry itself. I have created such a package at http://svn.zope.org/Sandbox/chrism/zope.registry It contains an implementation of the registry and the tests for the registry object. It depends on zope.interface and zope.event. I'd like to actually remove the zope.event dependency and release a newer version of zope.event that uses a global inside zope.registry as the list of registered object (reverse the dependency). After that's done, I'd suggest we make zope.component depend on zope.registry. At this point, people can innovate with their own APIs to the registry object as necessary; they needn't carry along the baggage of the expecation of the older zope.component API working in their app. Thoughts? FWIW, it's not of a lot of interest to me. I'm interested in changing things at a lower level. However that works, if I manage to build zope.component backwards compatibility as an add-on then I'll have to worry about all of the bits in zope.component, not just this. Gary ___ Zope-Dev maillist - Zope-Dev@zope.org https://mail.zope.org/mailman/listinfo/zope-dev ** No cross posts or HTML encoding! ** (Related lists - https://mail.zope.org/mailman/listinfo/zope-announce https://mail.zope.org/mailman/listinfo/zope )
