CODEWITHSUNDEEP
pythonvariablesglobal-variables
idk
idk

Reputation: 11

Python: How do I change a global variable when it is a paramter inside a function?

For example:

x = {'a':1, 'b':2}
y = {}

# only requirement: x and y has to be parameters of function foo
def foo(x,y):
    '''
    How do I switch the two variables inside this function without scope issues?
    '''

print('x =', x)
print('y =', y)

Result:

x = {}
y = {'a':1, 'b':2}

I tried putting global x, y and putting x,y = y,x inside the function but got this error as expected because they are already global:

SyntaxError: name 'x' is parameter and global
# Same thing happens for y

Upvotes: 1

Views: 1570

Answers (2)

Wasif
Wasif

Reputation: 15470

If you are working with global variables, don't take args ;-)

def foo():
  global x,y
  x,y = y,x

Enlightening on my alternate idea

def foo(x,y):
  return [y,x]

myList = foo(x,y)
x,y = myList[0], myList[1]

Upvotes: 1

Yash
Yash

Reputation: 108

x = {'a':1, 'b':2}
y = {}

def foo():
    global x,y  #bring global variable in func scope
    x,y = y,x #swaps variable variable values

def foo1():
    globals()['x'] = {'a':1, 'b':2}  #update value of global variable in func
    globals()['y'] = {}

#method1
foo()
print(x,y)

#method2
x = {'a':1, 'b':2}
y = {}
foo1()
print(x,y)

Both functions will work.

If you want to send the variable as args: check Pythons concept of mutability of variables. Additionally check this

Upvotes: 0

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