Re: Accessing 'mangled' class attrbutes

Steve Juranich wrote:
Gerard Flanagan wrote:

I tried that Steve but it didn't work, and i don't think I can do what
I want in any case. There is no method '__write' in the base class, it
is only declared as an instance attribute in the constructor, like so:

def __init__(self, file, encoding="us-ascii"):
...
self.__write = file.write
...

I tried putting '__write = None' at the class level (in the base class
XMLWriter) but then, although '_XMLWriter__write' appears in
'dir(HtmlWriter)', I get 'NoneType is not callable'.

I also tried 'def __write(self, text) : pass ' in the base class, but
then the code runs but doesn't write the text I want - and anyway, if
I'm going to change the base class, then i may as well just add the
'write_raw' method to the base directly!

It's just some toy code at any rate, and I've learnt something new!
Thanks for your reply.

Gerard


Make sure you're calling the super's constructor before you try and access
the mangled member. Then (I forgot this part), you can just call the
mangled member from `self'. Example follows.

<foo.py>
class A(object):
def __init__(self):
self.__foo = lambda x, y : x + y

class B(A):
def __init__(self, x, y):
# Make sure you're calling the super's constructor first.
super(B, self).__init__()
self.sum = self._A__foo(x, y)
</foo.py>

import foo
b = foo.B(3, 4)
b.sum
7


--
Steve Juranich
Tucson, AZ
USA


It's all becoming clear! Yes, calling the base constructor was all I
needed to do:

class HtmlWriter(elementtree.SimpleXMLWriter.XMLWriter, object):

def __init__(self, file):
super( HtmlWriter, self).__init__(file)

def write_raw(self, text):
self.flush()
self._XMLWriter__write(text)

-works a charm. Appreciate your help Steve, thanks again.

Gerard

.

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