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From: "Prasad, Ramit" <ramit.prasad@jpmorgan.com.dmarc.invalid>
To: Neil Cerutti <neilc@norwich.edu>, "python-list@python.org" <python-list@python.org>
Subject: RE: sax.handler.Contenthandler.__init__
Thread-Topic: sax.handler.Contenthandler.__init__
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Date: Fri, 30 Aug 2013 17:35:42 +0000
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Neil Cerutti wrote:
> This code is from The Python Cookbook, 2nd edition, 12.2 Counting
> Tags in a Document:
> 
> from xml.sax.handler import ContentHandler
> import xml.sax
> class countHandler(ContentHandler):
>     def __init__(self):
>         self.tags=3D{}
>     def startElement(self, name, attr):
>         self.tags[name] =3D 1 + self.tags.get(name, 0)
> 
> Isn't overriding __init__ a risky thing to do? The docs don't
> mention it as a method I should override, and also don't define
> what's in there or if I'd need to call the base class __init__.
> Moreover, startDocument is provided for parser setup.
> 
> As it happens, ContentHandler.__init__ isn't empty, so the above
> code could fail if the parser isn't prepared for _locator to be
> undefined.
> 
> Is the above code is an acceptable idiom?
> 
> --
> Neil Cerutti
> --

I think this is a bad idea unless you want to avoid the parent 
class __init__ specifically (in which case a comment stating 
why is mandatory). I do not like that this recipe shows behavior
that might be fine in this instance, but is not a good general 
practice.

     def __init__(self):
         super(ContentHandler, self).__init__()
         #OR ContentHandler.__init__(self)
         self.tags=3D{}

I personally think the super() line is better of the two options.

~Ramit



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