Difficult design decision which would be easy if PHP had multiple inheritance

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1

Short version: I need a behavior be both, a CActiveRecordbehavior and a CModel.

Long version.

One of my tables has a text column containing XML data (the AssessmentQuestion.data column), and since I don't know how the XML format would evolve over time, I decided to use a behavior to handle it according to two parameters: an xml format version and a type (currently it can be only "multichoice").

So far so good. The next decision I've made was to use a generalized AssessmentQuestionbehavior which should be inherited by classes like AssessmentQuestionbehavior_multichoice_1_1 and contain much of the underlying functionality for all the questions.

Beside that, AssessmentQuestionbehavior should actually follow the broker pattern, and detach itself in AssessmentQuestionbehavior::afterFind() & co in the detriment of the right class for the given type/version of the question (actually I plan to make it degradable, if it doesn't find version 2.4, it should iterate backwards until it finds a class, but that's another story).

Now, the problem is that questions should receive parameters over $_GET/$_POST, so each behavior should be able to use validators, scenarios, and all the features a CModel has. At the beginning I thought I wouldn't need to copy that much from CModel (only the functionality around CValidator::createValidator), but after 30 minutes of copying around I ended up with almost the entire code from CModel (since validators call addError() & co.).

Since I hate code duplication, right now I think about using a dummy CModel and wrap around it inside AssessmentQuestionbehavior (I think it's called the composite pattern).

What other alternatives would I have, especially tightly integrated into Yii?

Thanks.

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Maybe you can create a model instance in your behavior?

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Yes, that's what I was saying:

Quote

Since I hate code duplication, right now I think about using a dummy CModel and wrap around it inside AssessmentQuestionbehavior (I think it's called the composite pattern).

though I think it's called the proxy pattern.

I was curios if there would be any other, more convenient way provided by Yii itself.

4

Why not make a new class based on CModel with your augmentation and attached behaviors? Or am I not understanding your issue correctly?

5

Of course the dummy Cmodel I was referring to over here

Quote

Since I hate code duplication, right now I think about using a dummy CModel and wrap around it inside AssessmentQuestionbehavior (I think it's called the composite pattern).
will be a subclass of CModel, since otherwise I wouldn't be able to set the model's safe attributes, rules, attribute labels, and so on.

Actually it is already, I've already implemented it by this time. I was only curious if there would be any other way, possibly better.

Anyway, here's the code

Does it look ok? I have the feeling that it stills need to be polished up.

Note: reset() is there because the instance itself is going to be reused. It's not by itself a singleton, though, but the singletoness is forced by the caller (it's a static member of the caller, which is the base behavior)

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What exactly is "overriden" in this class?

Would you need to do that if you extended CActiveRecord instead of CModel?

And to your question for a better way, this is, IMHO, the proper way.