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<blockquote data-quote="PeterDonis" data-source="post: 342557" data-attributes="member: 6906">Thanks for the lucid exposition. I understand the pattern, and it's basically what I was thinking, but the issue is that at run time, each object has to know as it's created which other objects it needs to register with. That's what you need the (potentially massive) database table for--the alternative is to have every object register with every other, but then each object, as it's notified of another object's change, has to know whether that change will affect it, and if so, how. So again you still need a database table that tracks these cascading effects. I'm not saying the problem isn't solvable or that the pattern you've described isn't the right way to go--just that, even if the basic concept of the pattern is trivial, the implementation still isn't.Peter Donis(edit--P.S.) Another issue is that some cascading effects can happen when you add or delete an object rather than just changing its data, so objects also have to notify other objects when they are created or destroyed, and the other objects have to know how to deal with that too.</blockquote>

[QUOTE="PeterDonis, post: 342557, member: 6906"] Thanks for the lucid exposition. I understand the pattern, and it's basically what I was thinking, but the issue is that at run time, each object has to know as it's created which other objects it needs to register with. That's what you need the (potentially massive) database table for--the alternative is to have every object register with every other, but then each object, as it's notified of another object's change, has to know whether that change will affect it, and if so, how. So again you still need a database table that tracks these cascading effects. I'm not saying the problem isn't solvable or that the pattern you've described isn't the right way to go--just that, even if the basic concept of the pattern is trivial, the implementation still isn't. Peter Donis (edit--P.S.) Another issue is that some cascading effects can happen when you add or delete an object rather than just changing its data, so objects also have to notify other objects when they are created or destroyed, and the other objects have to know how to deal with that too. [/QUOTE]

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