Python Private Member Black Magic

gistfile1.py

class Vault(object):
    
    #here's our private variable
    __secret = "subtle and insubstantial, the expert leaves no trace"
    
    #getter method to return the secret variable
    def get_secret(self):
        return self.__secret
    
fort_knox = Vault()

try:
    #this will throw an error because __secret is private
    print fort_knox.__secret
    print "Accessed directly."
except:
    #print using our getter
    print fort_knox.get_secret()
    print "Accessed via getter."
    
#but, accessing private members from a getter is no fun
#let's take a walk on the wild side
print fort_knox._Vault__secret
print "Accessed via shadow attribute"

#how is that possible, you ask?
#let's run dir() on our fort_knox object
print dir(fort_knox)  

#you'll see that Python creates a shadow attribute for __secret
#so, nothing is really private

#can we change the value of __secret via its shadow attribute?
fort_knox._Vault__secret = "show him a road to safety, then strike."
    
try:
    #this will throw an error because __secret is private
    print fort_knox.__secret
    print "Accessed directly."
except:
    #print using our getter
    print fort_knox.get_secret()
    print "Accessed via getter."
    
#the answer is yes
#changing the shadow attribute changes the original attribute
#amazing. mind = blown