Problem scenario
You want to use the copy feature in Python. What do you do?
Solution
To see the different types of copying, use a mutable object such as a list. Here is an example:
import copy
var1 = [1, 2, 3, 4]
shallow_copy = var1
deep_copy = copy.deepcopy(var1)
var1.append(999999999999)
print()
print(shallow_copy)
print(" --- Shallow copy above and deep copy below ---.")
print(deep_copy)For most (or perhaps all) intents and purposes, you cannot shallow copy a string. You can shallow copy a list or other mutable object. This is how you can use the .copy() feature with a string (but notice how the effect of deep copying takes place):
import copy
var1 = "a sample string"
shallow_copy = var1
deep_copy = copy.deepcopy(var1)
var1 = var1 + " some extra text added later on -----------------------------------------"
print()
print(shallow_copy)
print(" --- Shallow copy above and deep copy below ---.")
print(deep_copy)If you cannot use the copy module (e.g., use "import copy") see this PoStInG: Why in Python Does a Variable Copy Get Changed when You Change Its Source?