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__
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__
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, 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 )
