James Stroud wrote:
The thread "why not arrays" got me thinking. I would really like to inherit from a list so that I can add methods based on its contents, say if I filled it with a type of object and wanted to iterate over all objects. I have built a wrapper around a list like this for general use:
class list_of_objects: def __init__(self): self.data = [] def __len__(self): return len(self.data) etc ...
Then it can be heritable and I can add or override methods. Why aren't built in lists and dictionaries real heritable types that can save this kind of patchwork? Is there a pythonic reason I am missing here?
James
But they *are* subclassable, since 2.2 at least:
PythonWin 2.2.1 (#34, Apr 15 2002, 09:51:39) [MSC 32 bit (Intel)] on win32.
Portions Copyright 1994-2001 Mark Hammond ([EMAIL PROTECTED]) - see 'Help/About PythonWin' for further copyright information.
>>> type(list)
<type 'type'>
>>> class my_list(list):
... pass
...
>>> type(my_list)
<type 'type'>
>>> l = my_list()
>>> l.append('foo')
>>> l.extend(['bar', 'baz'])
>>> l[2]
'baz'
>>> l
['foo', 'bar', 'baz']
>>> type(l)
<class '__main__.my_list'>
>>>
Jeff Shannon Technician/Programmer Credit International
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