Why does python behave so? (removing list items)

[=?ISO-8859-2?Q?Micha=B3_Bentkowski?=]

Why does python create a reference here, not just copy the variable?

>>j=range(0,6)
k=j
del j[0]
j

[1, 2, 3, 4, 5]

>>k

[1, 2, 3, 4, 5]

Shouldn't k remain the same?

--
Micha³ Bentkowski
mr*****@gmail.com

[Waldemar Osuch]

On Mar 26, 4:04 pm, "Micha³ Bentkowski" <[e-mail]:

Why does python create a reference here, not just copy the variable?

>j=range(0,6)
k=j
del j[0]
j

[1, 2, 3, 4, 5]

>k

[1, 2, 3, 4, 5]

Shouldn't k remain the same?

http://www.effbot.org/zone/python-list.htm

[Jarek Zgoda]

Micha³ Bentkowski pisze:

Why does python create a reference here, not just copy the variable?

Because Python works like that -- it uses names and values idiom. If you
change value, all names will be bound to the same changed value.

>>>j=range(0,6)
k=j
del j[0]
j

[1, 2, 3, 4, 5]

>>>k

[1, 2, 3, 4, 5]

Shouldn't k remain the same?

No further comments on this.

--
Jarek Zgoda
http://zgodowie.org/

"We read Knuth so you don't have to" - Tim Peters

[bearophileHUGS]

Micha³ Bentkowski:

Why does python create a reference here, not just copy the variable?

I think to increase performance, in memory used and running time (and
to have a very uniform way of managing objects).

Bye,
bearophile

[castironpi]

On Mar 26, 5:28*pm, [e-mail] wrote:

Micha³ Bentkowski:

Why does python create a reference here, not just copy the variable?

I think to increase performance, in memory used and running time (and
to have a very uniform way of managing objects).

Bye,
bearophile

A variable is a name-value pair. It's undefined outside of one-to-
ones therein. You have two names. Do they refer to the same object.
There is no such thing as the "primitive contents" of -any- standard
object.