[Tutor] lists, name semantics

[boB Stepp]

On Sat, Apr 18, 2015 at 3:28 PM, Bill Allen <wallenpb at gmail.com> wrote:
> On Apr 18, 2015 7:50 AM, "Peter Otten" <__peter__ at web.de> wrote:
>
>> Bill Allen wrote:
>>
>> > Everyone that responded,
>> >
>> > Thanks very much for the excellent explanations!  The distinction between
>> > a reference to an object and a seperate copy of the object is quite clear
>> > now.
>>
>> You can test your newfound knowledge by predicting the output of the
>> following script:
>>
>>
>> a = [1, ["x", "y"], 3]
>> b = a[:]
>>
>> a[1][1] = "hello!"
>>
>> print(a) # [1, ['x', 'hello!'], 3]
>> print(b) # what will that print?
>>
>> Think twice before you answer. What is copied, what is referenced?

> print(b) will print the original copy of a which b now references which is
> [1, ["x", "y"], 3]

Uh, oh! You should have checked your work in the interpreter before
replying! Peter is being very tricky!! (At least for me...) Look again
at that list inside of a list and...

boB

P.S.: Watch out for top-posting. That tends to get peopled riled. I
moved your response back into the normal flow of the interleaved
conversation.