The class is given below, this will print 20_20. Now till the line 5 code is same, I don't want the value of T.a to change when i change value of T1.a. How to solve it?
class Test:
def __init__(self, val):
self.a = val
T = Test(10)
T1 = T
T1.a = 20
print T.a + '__' + T1.a
Expected Output Is 10_20 .
In line 6. T1 = T, you are telling python to make a new reference to object T called T1.
i dont want the value of T.a to change when i change value of T1.a
This can't be done the way you set it up since T and T1 point to the same object. You can see this by noting that T is T1 evaluates to True in the python interpreter.
It seems maybe that you want to instantiate 2 Test objects, each with its own a property, so that changing one object won't affect the other.
The thing you want to do is probably called "deep copying" https://docs.python.org/2/library/copy.html
this allows you to create a copy of an existing object, instead of a reference. That is the closest thing to pass by value, I can think of, when using objects.
You could also use the copy method of the copy module:
import copy
T = Test(20)
T1 = copy.copy(T)
T1.a = 40
print T.a
# Output 20
print T1.a
# Output 40
For more info check out the copy docs, https://docs.python.org/2/library/copy.html
By making T1=T you are making both of them same so if you change T1 it will affect T and vice versa . You could use copy,deep copy etc
class Test:
def __init__(self, val):
self.a = val
T = Test (10)
T1 = Test(20)
print str(T.a) + '__' + str(T1.a)
see this link for more on mutuable and non-mutable object assignment and value changing
