On Apr 25, 2007, at 10:10 AM, johnf wrote:
> Since you took the time to explain scope and namespace could you
> explain "__"
> in context of Dabo. Why is it necessary to mangle functions?
The double-under is a convention that allows you to create a name
that will not be overridden by a subclass or instance. Python
accomplishes this internally by translating MyClass.__foo to
MyClass._MyClass__foo at runtime. So imagine that you have this class
structure:
class TheSuper(object):
def __foo(self):
print "Super Class"
class TheSub(TheSuper):
def __foo(self):
print "Sub Class"
obj = TheSub()
At this point, obj does *not* have a __foo() method, even though it
is defined in both of its superclasses. It does have a _TheSub__foo()
and a _TheSuper__foo() method, though.
While this is often cited as a way of creating private members, it's
actually not designed for that at all; its main purpose is to provide
protected members that cannot be accidentally overridden by a subclass.
-- Ed Leafe
-- http://leafe.com
-- http://dabodev.com
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