importing variable from module in python makes copy?

Question

It seems like doing from foo import i makes a copy of i rather than importing i into the current namespace. Is that possible?

foo.py:

i=0
<         


        

Answer 1

just aliases for the same memory as it were

You misunderstood how "variables" work in python. Variables are not memory locations. They are just names attached to objects. When you perform the assignment:

i = 0

you are giving the name i to a new object 0 in the current scope.

You should read the documentation about naming and binding

---

Maybe a diagram can make this clearer:

Situations before modifying i:

foo.i       i
  |        /
  |       /
  |      /
  |     /
  |    /
  |   /
  |  /
+-----+
| 999 |
+-----+

The object 999 has two references. When you do:

i = 0

This is what happens:

foo.i         i
  |           |
  |           |
  |           |
  |           |
  |           |
  |           |
  |           |
+-----+     +---+
| 999 |     | 0 |
+-----+     +---+

If you want to modify the value of the 999 object... well: you can't because in python integers are immutable.

Note that it doesn't have to do with scopes:

i = 999
j = i
i = 0
print(i, j)  # prints: 0 999

The names i and j are just labels to objects. If you come from C you may think of every python variable as a pointer to the actual object. As if the above code was:

int *i = &999;
int *j = i;
i = &0;
printf("%d %d", *i, *j);