At 10:28 AM 8/10/00 +0200, RC Compaan wrote:
>Oh ok, this divide clears it up a bit. I somehow imagined that an object's
>properties are always stored inside the object and that Providers are the
>managers of those properties.
I am finding that most people outside of Digital Creations aren't aware
that there's any other kind of property sheet besides the kind that stores
its data in attributes. :(
>The Specialist (filing clerk) asks its racks (filing cabinet) for an object
>(dental records). The rack (filing cabinet) tells the object (the dental
>records) that it belongs to the rack AND that the object should ask the rack
>for anything it needs.
>Why would the object "need" anything. Is it not the specialist with the
>If object data is stored external to the dataskin object does the dataskin
>only implement behaviour? I find it difficult to understand because I
>associate Dataskin with Storage.
DataSkins do not implement storage; the whole point of a DataSkin is that
it is storage-neutral. It is a behavioral "skin" which can be wrapped over
other objects which actually implement behavior. It's a rather
sophisticated variant of the GOF "Strategy" pattern, where an object
delegates the choice of algorithm to another object.
> If object data is stored externally is it
>stored in Persistent Property Sheets?
Well, that's one way to do it, and the only way implemented for you in
ZPatterns currently. If you want to do it another way (e.g. SQL), you'll
have to write your own sheet provider.
>How does one define properties for
>Persistent Property Sheets?
By calling the standard propertysheet methods to manipulate their
properties from code, e.g. manage_editProperties and the like.
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