Python how to pass variable between two def

Question

I would pass a variable between two def inside a function. How can i do? i tried using global but didn't work

class example:

 def funz1(self,q,b):
    global queue
    queue = []
    queue += [q]
    queue += [a]

 def funz2(self):
    return str(queue.pop())

but it said me that queue is an empty list

score 4 · Accepted Answer · edited May 23 '17 at 12:20

4

You have to use the self parameter, which points to the example instance itself:

class example:    
 def funz1(self,q,b):
    self.queue = []
    self.queue += [q]
    self.queue += [a]

 def funz2(self):
    return str(self.queue.pop())

Read more here.

Also, as a side note, array += [item] is wrong, you should use array.append(item)

edited May 23 '17 at 12:20

Community

1
1

answered Feb 27 '12 at 11:49

Gabi Purcaru

30,940
9
79
95

but self has no attribute 'queue' – fege Feb 27 '12 at 11:57
@fege you create on the `self.queue = []` line – Gabi Purcaru Feb 27 '12 at 11:58
if i want pass the variable between the def without the class? – fege Feb 27 '12 at 11:59
in self of funz1 i have a list so when i run your code it answer me 'list' object has no attribute 'queue' – fege Feb 27 '12 at 12:01

mandel · Answer 2 · 2012-02-27T15:25:10.873

There are several issued with that code, first, there is no need to use a global bar since you can access self. Also, pop will raise an exception if the list is not empty, therefore, you can have the following:

class example:    
    def __init__(self):
        self.queue = []

    def funz1(self,q,b):
        self.queue.append(q)
        self.queue.append(b)

    def funz2(self):
        if len(self.queue) > 0:
            return str(self.queue.pop())

On top of that, if you are using a list as a q you might as well use deque from collections which was designed for that use:

from collections import deque

class example:    
    def __init__(self):
        self.queue = deque()

    def funz1(self,q,b):
        self.queue.append(q)
        self.queue.append(b)

    def funz2(self):
        if len(self.queue) > 0:
            return str(self.queue.popleft())

Python how to pass variable between two def

2 Answers2