Fix and simplify recursion

palindrome.py

@@ -12,22 +12,25 @@ def parse_args():
                                                   'transform it into a'
                                                   'palindrome'))
     parser.add_argument('-i',
-                        '--int',
+                        '--integer',
                         required=True,
                         help='The integer to be transformed.',
                         type=int)
     # NOTE: The argument must be an integer. Because of this constrain integers
-    # with leading zeroes will be stripped automatically in python 3.
+    # with leading zeroes will be stripped automatically in python 3. Also the
+    # script only allows integers as an input defined by type=int
     args = parser.parse_args()
     return args
 
 
 def main():
     args = parse_args()
-    if args.int <= 10000 and args.int > 0:
-        print('Input integer is: {}'.format(args.int))
+    if args.integer <= 10000 and args.integer > 0:
+        print('Input integer is: {}'.format(args.integer))
         transform = Transform()
-        palindrome = transform.palindrome(args.int)
+        palindrome = transform.palindrome(args.integer)
+        if palindrome == transform.INVALID_RETURN_VALUE:
+            print('Palindrome to be calculated is to big. Abort!')
         print("Final Output is:", palindrome)
         return palindrome
     else:

transform/Transform.py

@@ -2,56 +2,57 @@
 # -*- coding: utf-8 -*-
 class Transform(object):
     """Class to transform a given integer into a palindrome"""
+    # to avoid magic numbers.
+    MAXIMUM_INPUT_VALUE = 1000000000
+    INVALID_RETURN_VALUE = -1
 
     def __init__(self):
         super(Transform, self).__init__()
 
-    def palindrome(self, int):
+    def palindrome(self, integer):
         '''
-        Kind of the main function. Checks if input int is already a palindrome
-        and trys calculation one if input integer is not already a palindrome.
+        The main function. Checks if input integer is already a palindrome
+        and trys calculating one if input integer is not already a palindrome.
         '''
-        self.input_int = int
-        if self.__is_palindrome(self.input_int):
-            print('Integer {} is a palindrome'.format(self.input_int))
-            return self.input_int
+        self.input_integer = integer
+        if self.__is_palindrome(self.input_integer):
+            print('Integer {} is a palindrome'.format(self.input_integer))
+            return self.input_integer
         else:
-            print('Integer {} is not a palindrome'.format(self.input_int))
-            print('Calculating the palindrome for input {}'.format(self.input_int))
+            print('Integer {} is not a palindrome'.format(self.input_integer))
+            print('Calculating the palindrome for input {}'.format(self.input_integer))
             palindrome = self.__calculate_palindrome()
             return palindrome
 
     # The following methods are private. Signaled by the leading __
     def __is_palindrome(self, int_to_check):
-        reversed = self.__reverese_int(int_to_check)
-        if self.input_int == reversed:
+        reversed_integer = self.__reverese_int(int_to_check)
+        if self.input_integer == reversed_integer:
             return True
         else:
             return False
 
     def __reverese_int(self, int_to_reverse):
-        reversed = 0
+        reversed_integer = 0
         int_to_check = int_to_reverse
         while int_to_check > 0:
             reminder = int_to_check % 10
-            reversed = (reversed * 10) + reminder
+            reversed_integer = (reversed_integer * 10) + reminder
             int_to_check = int_to_check // 10
-        return reversed
+        return reversed_integer
 
     def __calculate_palindrome(self):
-        reversed = self.__reverese_int(self.input_int)
-        self.input_int = self.input_int + reversed
-        print('Possible palindrome is {}'.format(self.input_int))
-
-        if self.__is_palindrome(self.input_int) is True:
-            return self.input_int
-
-        if self.__is_palindrome(self.input_int) is False:
-            return self.__try_again()
-
-    def __try_again(self):
-        while self.input_int <= 1000000000:
-            self.__calculate_palindrome()
-            if self.input_int >= 1000000000:
-                print('Palindrome to be calculated is to big. Abort!')
-        return -1
+        reversed_integer = self.__reverese_int(self.input_integer)
+        self.input_integer = self.input_integer + reversed_integer
+        print('Possible palindrome is {}'.format(self.input_integer))
+        if self.__is_palindrome(self.input_integer) is True:
+            print('Possible palindrome is correct!')
+            return self.input_integer
+        elif not self.__is_palindrome(self.input_integer):
+            print('Possible palindrome is wrong! Calcualte again!')
+            while not self.__is_palindrome(self.input_integer):
+                if self.input_integer >= self.MAXIMUM_INPUT_VALUE:
+                    return self.INVALID_RETURN_VALUE
+                else:
+                    self.__calculate_palindrome()
+            return self.input_integer