a simple example of the ZPatterns frame work
Hello, I wonder if someone can send me a simple example using the ZPatterns framework. I read all the source, and I still can't figure out what is the relationship between the objects instantiated by the Racks and the Rackmountable objects. Also, why do the rack try to instantiate a ZClass??? I'm lost. The LoginManager code does not answer my question because the generic user source does not instantiate any object. comments ? Regards, Jephte CLAIN minf7@educ.univ-reunion.fr
At 08:39 PM 5/17/00 +0400, Jepthte CLAIN wrote:
I wonder if someone can send me a simple example using the ZPatterns framework. I read all the source, and I still can't figure out what is the relationship between the objects instantiated by the Racks and the Rackmountable objects. Also, why do the rack try to instantiate a ZClass???
When created, Racks create some default Attribute and Sheet providers. These objects are used by Rackmountables to access data which is not stored directly in the rackmountable. When used, Racks create instances of the ZClass you've specified. If you call newItem(key), you will receive a new instance of that ZClass, which will be stored in the rack under the specified key. Whenever you call getItem(key), the instance will be retrieved. Some Racks, like GenericUserSource, do not store items in themselves, but in external databases. When you call getItem(key) on a GUS, it calls methods to access the external database, then creates an instance of the appropriate LoginUser subclass and returns that. Hope that helps; I'm not 100% clear on your question.
"Phillip J. Eby" wrote:
At 08:39 PM 5/17/00 +0400, Jepthte CLAIN wrote:
I wonder if someone can send me a simple example using the ZPatterns framework. I read all the source, and I still can't figure out what is the relationship between the objects instantiated by the Racks and the Rackmountable objects. Also, why do the rack try to instantiate a ZClass???
When created, Racks create some default Attribute and Sheet providers. These objects are used by Rackmountables to access data which is not stored directly in the rackmountable.
When used, Racks create instances of the ZClass you've specified. If you call newItem(key), you will receive a new instance of that ZClass, which will be stored in the rack under the specified key. Whenever you call getItem(key), the instance will be retrieved. Some Racks, like GenericUserSource, do not store items in themselves, but in external databases. When you call getItem(key) on a GUS, it calls methods to access the external database, then creates an instance of the appropriate LoginUser subclass and returns that.
Hope that helps; I'm not 100% clear on your question.
It helps me a litle. I think what Jepthe was asking for though, is a simple howto. For example, lets say I wanted to implement a image-like object that stored the actual in a SQL database, for example, with 'meta' information (photographer, date, category, etc) stored in the ZODB for indexing and management. A walkthrough on how to do this would be especially useful at this stage. At least, that's what I interpreted Jepthe as wanting. no-my-desire-for-this-colored-my-perception-in-way-:^)-ly y'rs Bill
participants (3)
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Bill Anderson -
Jepthte CLAIN -
Phillip J. Eby