Odoo Server (MOVED TO GITHUB)

Class Inheritance in OpenERP

Asked by Cuong

Hi,

I have confused on class inheritance. Take an example. I have 3 classes: A, A1, A2 (these use class inheritance)

- In class A: I override osv write() method to do some general jobs.
- In class A1: A1 inherited from class A. I also override write() method
- In class A2: A2 inherited from class A. Method write() also is overridden.

Now, in class B, there are some codes like this
===
a_obj = self.pool.get('a')
a = a_obj.write(cr, uid, a_id, context=context)
===
 When write method is called, what happens? It will call A1's write() method, A2's write() method, A's write() method?

Please help me make clear this. In practice, I use a lot of inheritance, so I need to know the order of execution of the above write() call.

Thank you very much.

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Numérigraphe (numerigraphe) said : 		#1

It will call the one that was loaded the last when the server initialized.
So you have to take care that :
- each call's it's superclass's write() method
- if each class is in a different module, the dependencies make sure A is loaded before A1 and A2.
Lionel Sausin.

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Cuong (bhcuong2008) said : 		#2

Hi,

In my case, each class exists in different module. A exists in the base module. A1, A2,.. exist in-dependency. It means A1 will require A. A2 will require A.

With your suggestion, there are 2 cases:
1. Just install A1, then when calling a_obj.write() will result in calling a1.write()

2. Install both A1, A2. How do I know the order of server initialization. A1 before A2 or A2 before A1? If A1 before A2, it will call a2.write(). Otherwise, A2 before A1, a1.write() will be called ?

In this case, a1.write() or a2.write() will be never called! How do I want to call specific a1.write() / a2.write() with self.pool.get('a').write()?

Thanks,

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Numérigraphe (numerigraphe) said : 		#3

Please understand that the openerp model's inheritance structure is distinct from python's class inheritance structure.
So, as long as you call super()'s method, the framework takes care of the rest. Trust it.

If you install A1 only: write() will call a1.write(), which will calls a.write()
if you install A1 before A2: write() will call a2.write(), which will call a1.write(), which will call a.write()
if you install A2 before A1: write() will call a1.write(), which will call a2.write(), which will call a.write()

If you do need a specific execution order, you must inform the framework with "depends".
Lionel.

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Cuong (bhcuong2008) said : 		#4

Thank you for your clear explanation.

You mention "depends", do you mean "depends" defined in file __openerp__?

Thank you very much,

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Numérigraphe (numerigraphe) said : 		#5

Yes, "depends" from __openerp__.py .
Lionel.

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