Python: luhn

python/luhn/luhn.py

@@ -0,0 +1,30 @@
+import re
+
+class Luhn:
+    def __init__(self, card_num):
+
+        pattern = re.compile(r'\s+')
+        card_num = re.sub(pattern, '', card_num)
+
+        if not card_num.isnumeric() or len(card_num) < 2:
+            self.is_valid = False
+        else:
+
+            checksum = 0
+
+            for i, ch in enumerate(reversed(card_num)):
+
+                x = int(ch)
+
+                if i % 2:
+                    x *= 2
+
+                    if x > 9:
+                        x -= 9
+
+                checksum += x
+
+            self.is_valid = not (checksum % 10)
+
+    def valid(self):
+        return self.is_valid