jonocarroll · December 16, 2024 22:44 · Dec 16, 2024
diff --git a/py_mutable_args.py b/py_mutable_args.py
@@ -0,0 +1,25 @@
+>>> def make_a_list(val1 = 0, val2 = 0, lst = []):
+...    lst.append(val1)
+...    lst.append(val2)
+...    return lst
+
+>>> # you need to know that you're modifying base_list
+>>> base_list = [1, 2, 3, 4]
+>>> extend_list = make_a_list(5, 6, base_list)
+>>> print(extend_list)
+[1, 2, 3, 4, 5, 6]
+
+>>> # so it's now the same as extend_list
+>>> print(base_list)
+[1, 2, 3, 4, 5, 6]
+
+>>> # good luck if you don't know it's referenced
+>>> # in this case lst = [] is defined at 
+>>> # function definition and is mutable
+>>> my_list = make_a_list(3, 4)
+>>> print(my_list)
+[3, 4]
+
+>>> other_list = make_a_list(7, 8)
+>>> print
+[3, 4, 7, 8]