Problem with assigning variables of type List
mwh at python.net
Wed Aug 21 05:52:08 EDT 2002
Peter Hansen <peter at engcorp.com> writes:
> Abhishek Roy wrote:
> > "Fredrik Lundh" <fredrik at pythonware.com> wrote in message news:<xiu89.5146$HY3.1421847 at newsc.telia.net>...
> > > ... you have to say something like "the object referred to
> > > by x is passed by reference". Or alternatively, "x is passed
> > > by value, and that value is a reference to an object". Just
> > > calling it "pass by reference" or "pass by value" are both
> > > half true and half false.
> > I'm still not quite sure what that means but after reading,
> > http://effbot.org/guides/python-objects.htm
> > I experienced a lovely feeling of enlightenment.
Quite: it's much more important to understand how it works than what
it's called. Call by binding, anyone? Oh, I just don't care.
> > Just a nagging doubt, using the terminology in the above guide what's going
> > on with:
> > >>> a=[1,2,3]
> > >>> a=a
> > >>> a
> > [1, [...], 3]
> > >>> a==a
> > 1
> You created a recursive object, which contains a reference to
> itself. Since this goes down infinitely deep, and you can't compare
> infinities, I thought, I wonder whether the "1" is mathematically
> true. It is certain true according to Python's rules though.
we're already scrubbing the face of intuition with steel wool,
setting it on fire, then putting it out with an axe <wink>.
-- Tim Peters, on comparing recursive structures
That one is easily explained away as massively intricate
conspiracy, though. -- Chris Klein, alt.sysadmin.recovery
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