Re: [Zope-dev] Extension class and __init__
Ross Boylan writes:
The example there is basically
class Spam:
def __init__(self):
...
class ECSpam(Base, Spam): #Base is an ExtensionClass
def __init__(self):
ECSpam.inheritedAttribute('__init__')(self)
I started to use the following idiom:
class ECSpam(...,Spam): ...
_Spam__init= Spam.__init__
def __init__(self):
self._Spam__init()
i.e., rename the overloaded method in you derived class and call
it in the normal way with its new name.
Dieter
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Re: [Zope-dev] Extension class and __init__
From: Adrian Hungate [EMAIL PROTECTED] Erm... that trashes the concept of mixin's, doesn't it? No, why would it? Just make your mixins inherit Extentionclass.base! If you have third-party mixins that aren't made for Zope from the beginning and need initailization, then you probably have to Zopify them first. I don't see how this is convoluted. It's not obvious to non-Zope gurus, but that is what comments are for. :-) ___ Zope-Dev maillist - [EMAIL PROTECTED] http://lists.zope.org/mailman/listinfo/zope-dev ** No cross posts or HTML encoding! ** (Related lists - http://lists.zope.org/mailman/listinfo/zope-announce http://lists.zope.org/mailman/listinfo/zope )
Re: [Zope-dev] Extension class and __init__
Ross Boylan wrote:
class ECSpam(Base, Spam): #Base is an ExtensionClass
def __init__(self):
ECSpam.inheritedAttribute('__init__')(self)
What if you have more than one base class with the method defined?
The normal Python inheritted attribute lookup rules: depth first, left to right
through the list of base classes.
The implication of th example is that the non-extension class base
class is used
If Spam defines __init__ and Base doesn't, that would be the case...
(though even that is not clear; would this work if Base
had __init__?),
No, in that case Base's __init__ would be used, see python inheritence rules.
but what if there are several non-extension base
classes?
See python inheritence rules...
The syntax doesn't provide a way of indicating which class you want
the method from, and so it seems incomplete.
Well, if you wanted it to come from Base specifically, you could do:
Base.inheritedAttribute('__init__')(self)
not sure about the non-EC bases, perhaps Jim could clarify this?
cheers,
Chris
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Re: [Zope-dev] Extension class and __init__
Ross, Please see the bit about inheritedAttribute in the document inside Zope's source tree named lib/Components/ExtensionClass/doc/ExtensionClass.html. HTH, - C - Original Message - From: Ross Boylan [EMAIL PROTECTED] To: [EMAIL PROTECTED] Cc: Ross Boylan [EMAIL PROTECTED] Sent: Monday, July 22, 2002 3:30 AM Subject: [Zope-dev] Extension class and __init__ I had the bright idea of defining a mixin class whose methods I thought I could use in my regular Zope product classes: class AMixin: def __init__(self): blah, blah blah class B(AMixin, Persistent, Folder, ): def __init__(self): # do some of my own stuff AMixin.__init__(self) This fails with the warning (as I recall) that the unbound method AMixin.__init__ needs to be called with an instance as its first argument. (I've stripped the example down to give what I think are the essentials). self in the context of B is an Extension class, and I'm guessing this is making AMixin unhappy because it's not. I assume I'll have the same problem with other methods that I attempt to access using AMixin.foo(self). Can anyone confirm this diagnosis? And what's the best solution? I have redefined things class AMixin: def _mixin_init(self): #stuff class B(AMixin, .): def __init__(self): #my own stuff self._mixin_init(self) and this seems to work, but I wonder if there's a way to get the classes to play together better (maybe class AMixin(ExtensionClass):? though since ExtensionClass is a type I guess that's not exactly it). This was after already discovering that isinstance doesn't work with ExtensionClass (which I see confirmed on the list, along with the fact that ExtensionClass generally has a lot of rough spots and may be on the way out). This is with Zope 2.5.1. ___ Zope-Dev maillist - [EMAIL PROTECTED] http://lists.zope.org/mailman/listinfo/zope-dev ** No cross posts or HTML encoding! ** (Related lists - http://lists.zope.org/mailman/listinfo/zope-announce http://lists.zope.org/mailman/listinfo/zope ) ___ Zope-Dev maillist - [EMAIL PROTECTED] http://lists.zope.org/mailman/listinfo/zope-dev ** No cross posts or HTML encoding! ** (Related lists - http://lists.zope.org/mailman/listinfo/zope-announce http://lists.zope.org/mailman/listinfo/zope )
