python: accessing class variable with or without reference

Question

code:

class Example:

    pos_list=[]
    last_cell=0

    def setText(self):
        last_cell = 10
        pos_list.append(int(10))              #Line 1
        print pos_list , last_cell            #Line 2

Error: global name 'pos_list' is not defined.

if i access pos_list in Line 1 and Line 2 as

   self.pos_List or Example.pos_list

then no error [ which is fine as i'm accessing it as a instance(self) or class(Example) variable ]

but what about last_cell ? i am accessing it without either self or class reference. But in case of pos_list python interpreter was forcing me to use either those two references.

why am able to access last_cell without any reference ?

Please do the official Python tutorial - Python's object model is quite different from what you may have learned from more mainstream OOPLs. — bruno desthuilliers
– bruno desthuilliers, Commented Apr 29, 2013 at 18:21

user395760 · Accepted Answer · 2013-04-29 17:46:19Z

4

You aren't. You're just creating a local variable that happens to have the same name.

class Example:
    x = 1
    def f(self):
        x = 2
Example().f()
print(Example.x) #=> 1

answered Apr 29, 2013 at 17:46

user395760

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Comments

alexn · Accepted Answer · 2013-04-29 17:46:07Z

0

Because you declare last_cell as a local variable. When doing pos_list.append() you are trying to call a method on something that is undefined, which generates an error.

answered Apr 29, 2013 at 17:46

alexn

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