Changing value of a python variable whose name is in a string [duplicate]

Question

Before you say to use a dictionary, I want to change the value of the actual variable.

This is what happens with the standard dict strategy: (Note that I'm not necessarily using a list, the value could be a complex class type or just a regular int)

>>> dict = {}
>>> x = [1,2,3]
>>> dict["x"] = x
>>> x
[1, 2, 3]
>>> dict["x"]
[1, 2, 3]
>>> dict["x"] = [4,5,6]
>>> dict["x"]
[4, 5, 6]
>>> x
[1, 2, 3]
>>>

Anyone know a way to do this so that the actual contents of x are changed as well? copy.deepcopy doesn't do the trick either. (as in 'dict["x"] = copy.deepcopy(x)')

Answer 1

Use slice assignment:

>>> d = {}
>>> x = [1, 2, 3]
>>> d['x'] = x
>>> d['x'][:] = [4, 5, 6]
>>> x
[4, 5, 6]
>>> d['x']
[4, 5, 6]

For other data types make sure you modify them in-place instead of assigning them to new variables. Note that for immutable data types like int, strings etc there are no in-place operations available.

Answer 2

this is a horrible idea and stinks of horrible code smell ... dont do this you need to refactor the code to be sensible .... this is a terrible idea but if you want

mutables = {
"x":x,"y":y,"Z":Z #make sure the dict key is exactly the same as var name
}

mutables['x'] = [5,6,7]
for k,v in mutables.items():
    globals()[k] = v

note that you will need to be in the same global scope as the original variables