The HPI Seaside tutorial shows the data models as subclasses of Object, and I have seen that elsewhere. However, some examples talk about finding the closest class to use as your starting point. I am curious what experienced Squeakers do.
Subclassing Object presumably gives maximum flexibility, but perhaps means that one ends up building in functionality that already exists further down the tree. On the other hand, taking a more specific class, might be a bit like premature optimisation?
Cheers AB
You'll only really subclass something if you are creating a specialisation of it. Most of the time not :-)
Start with Object.
I usually create my own "Model" base class for my application (subclass of Object). I have an application right now called Epic, so I have an EpicModel. It makes a convenient home for shared functionality.
Don't fall into the trap of subclassing collections. You almost always want your domain object to have a collection, not be a collection.
It has been rare in my applications to have domain models that are subclasses of something already in the image. Honestly can't think of it happening once (though I'm sure that it has).
The domain is one place where you can be really clean. You usually don't have that luxury in the presentation, controller, persistence, etc.
On Sun, Aug 17, 2008 at 6:19 PM, Andy Burnett andy.burnett@knowinnovation.com wrote:
The HPI Seaside tutorial shows the data models as subclasses of Object, and I have seen that elsewhere. However, some examples talk about finding the closest class to use as your starting point. I am curious what experienced Squeakers do.
Subclassing Object presumably gives maximum flexibility, but perhaps means that one ends up building in functionality that already exists further down the tree. On the other hand, taking a more specific class, might be a bit like premature optimisation?
Cheers AB
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It has been rare in my applications to have domain models that are subclasses of something already in the image. Honestly can't think of it happening once (though I'm sure that it has).
I can only think of one time I've ever done this, my Money object subclasses Magnitude, beyond that I've never found a reason to subclass anything but Object or another one of my own domain objects.
Ramon Leon http://onsmalltalk.com
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