List sequential initialization
steve at holdenweb.com
Tue Jun 19 03:46:54 CEST 2007
Chris Mellon wrote:
> On 6/12/07, HMS Surprise <john at datavoiceint.com> wrote:
>> Thanks for the explaination. It didn't seem natural and from the
>> tutorial I read:
>> A value can be assigned to several variables simultaneously:
>> >>> x = y = z = 0 # Zero x, y and z
>> Maybe I infer too much....
> And yet, your answer is right there.
> "A value can be assigned to several variables simultaneously"
> When you say want a value assigned to several variables, Python
> doesn't assume that you actually mean you want 2 different values
> assigned to them.
The crucial difference between
a = b = "ab"
a = "a"
a = b = ['a', 'b']
is that in the first case two names are bound to the immutable object
"ab". Then the first name is rebound to a different immutable object.
In the second example, both names are bound to the same mutable object,
a list. That object is then modified. The modification can be performed
using either name, and both names continue to point to the same (but now
Steve Holden +1 571 484 6266 +1 800 494 3119
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