How to pass by reference in Python?

Question

I just discovered that there are no ways to pass a var by reference in Python. From what I've seen this does not even exist in this language, which sounds strange to me, because I'm used to languages ​​derived from C, such as C# or C++, for example. The question is, if this does not actually exist in Python, how can I get the same result?

Answer 1

strawdog

Technically, yes, but you cannot assign to them in the function body:

def x(y):
x = 2 # here, x becomes a local variable inside the function

a = 1
print(a) # 1
x(a)
print(a) # still 1

You can still mutate mutable structures, like lists, though:

def x(y):
y.append(2)

a = [1]
print(a) # [1]
x(a)
print(a) # [1, 2]

Anyway, essentially, passing by reference is limited and can't be controlled by the programmer. Mutable objects (lists, dicts, class objects, etc.) can be used as a reference, but immutable objects cannot, and reassigning anything makes it a local variable (excluding **kwargs, that's a topic for another day). I think the purpose of this was to make the language easier to understand, and have only one way of doing things, a Python philosophy.

Answer 2

Better answer than I could write: https://stackoverflow.com/questions/986006/how-do-i-pass-a-variable-by-reference

Answer 3

The point is that in Python every var IS a reference.
>>> var = "a variable"
>>> def checkid(x):
print(id(x))
print(id(var))
>>> id(var)
48941960
>>> checkid(var)
48941960
48941960
>>>

Answer 4

Thank you guys!