Is a list an instance of a class?
danb_83 at yahoo.com
Mon Nov 15 13:01:05 CET 2004
Kent Johnson <kent3737 at yahoo.com> wrote in message news:<4197c013$1_1 at newspeer2.tds.net>...
> In the Python tutorial section 9.1, it says, "the word ``object'' in
> Python does not necessarily mean a class instance. Like C++ and
> Modula-3, and unlike Smalltalk, not all types in Python are classes: the
> basic built-in types like integers and lists are not, and even somewhat
> more exotic types like files aren't."
> Is this still correct or was it made obsolete by Python 2.2? Lists and
> files have __class__ attributes, at least:
For all practical purposes, it's obsolete. You can inherit from "non-classes" now.
>>> class TallyMarks(int):
... def __repr__(self):
... return 'I' * self
> >>> .__class__
> <type 'list'>
> >>> f = open('ThreadQueue.py')
> >>> f.__class__
> <type 'file'>
> So do integers and floats, though you have to ask nicely for an int:
> >>> 1.__class__
> File "<stdin>", line 1
> SyntaxError: invalid syntax
> >>> x=1
> >>> x.__class__
> <type 'int'>
You don't have to ask *that* nicely.
>>> 1 .__class__ # notice the space
More information about the Python-list