Question

I used the following stack class in Python to store objects of another class.

class Stack :
 def __init__(self) :
   self.items = []

 def push(self, item) :
   self.items.append(item)

 def pop(self) :
   return self.items.pop()

 def isEmpty(self) :
   return (self.items == []) 
scopeStack=Stack();
object1=AnotherClass();
object1.value=2;
scopeStack.push(object1);

On changing the contents of the object object1 outside the stack, the contents of the stack’s object changed too.

 object1.value=3;
 obj=scopeStack.pop();
 print obj.value; #gives output 3

What should I do to NOT have this dynamic binding between a local variable and the stack’s inner variables?

Answer 1

Check out the copy module found here. What you are looking for is called copy.deepcopy().

Example:

class Obj:
    def __init__(self, value):
        self.value = value

x = Obj(5)
y = copy.deepcopy(x)

print 'x:', x.value
print 'y:', y.value

x.value = 3

print 'x:', x.value
print 'y:', y.value

Output:

x: 5
y: 5
x: 3
y: 5