Rick Johnson於 2013年2月13日星期三UTC+8上午1時48分07秒寫道：
> On Monday, February 11, 2013 11:55:19 PM UTC-6, Chris Angelico wrote:
>
> > On Tue, Feb 12, 2013 at 12:06 PM, 88888 Dihedral wrote:
>
> > > A permanently mutated list is a tuple of constant objects.
>
> >
>
> > I nominate this line as "bemusing head-scratcher of the week".
>
>
>
> Actually the statement is fact IF you can grok it through the eyes of clarity.
>
>
>
> "A permanently mutated list..."
>
>
>
> A list that has been mutated permanently, that is, it cannot be changed back
> into a list. psst: i have a sneaking suspicion that he his referring to
> tuples, let's see.
>
>
>
> "...is a tuple..."
>
>
>
> Ha! Well in Python the immutable sequence type /is/ a tuple after all.
>
>
>
> "...of constant objects..."
>
>
>
> The tuple contains objects, and it's objects will maintain a constant
> ordering (relatively in tuple structure) until until the tuple's death.
>
>
>>> a1=[1,2,3]
>>> tuple1=(a1,4,5,6)
>>> tuple1
([1, 2, 3], 4, 5, 6)
>>> a1=[1,2]
>>> tuple1
([1, 2, 3], 4, 5, 6)
>>>
Yes, a tuple of constant objects is still not clear.
>
> Your confusion may stem from interpreting "constant" as the CS term
> "CONSTANT"[1]; whereby the objects in the tuple are programming CONSTANTS,
> that is, unable to change. But in reality, although a tuple (bka:StaticList)
> cannot expand to add more objects, or shrink to eject existing objects, the
> objects themselves CAN change their own internal state WITHOUT disrupting the
> immutable harmony of the tuple.
>
>
>
> Observe:
>
>
>
> py> class Foo(object):
>
> pass
>
> py> foo = Foo()
>
> py> t = (1,'1', foo)
>
> py> t
>
> (1, '1', <__main__.Foo object at 0x0267BF50>)
>
> py> t[-1].bar = "abc"
>
> py> t
>
> (1, '1', <__main__.Foo object at 0x0267BF50>)
>
>
>
> Or by expanding a list
>
>
>
> py> t = (1,2,3)
>
> py> t = t+([],)
>
> py> t
>
> (1, 2, 3, [])
>
> py> t[-1].append('circus')
>
> py> t
>
> (1, 2, 3, ['circus'])
>
>
>
> [1] Which is an unfortunate side-effect of polysemy and compounded
> exponentially by naive (and sometimes a purely malevolent intent when)
> transformation of words into esoteric problem domains.
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