Python: Make code testable

Avoid executing code on module level as this prevents importing the
module for testing. Especially infinite loops are evil.

33_Dice/python/dice.py

@@ -28,50 +28,54 @@
 
 import random
 
-# We'll track counts of roll outcomes in a 13-element list.
-# The first two indices (0 & 1) are ignored, leaving just
-# the indices that match the roll values (2 through 12).
-freq = [0] * 13
+
+def main():
+    # We'll track counts of roll outcomes in a 13-element list.
+    # The first two indices (0 & 1) are ignored, leaving just
+    # the indices that match the roll values (2 through 12).
+    freq = [0] * 13
+
+    # Display intro text
+    print("\n                   Dice")
+    print("Creative Computing  Morristown, New Jersey")
+    print("\n\n")
+    # "Danny Freidus"
+    print("This program simulates the rolling of a")
+    print("pair of dice.")
+    print("You enter the number of times you want the computer to")
+    print("'roll' the dice.   Watch out, very large numbers take")
+    print("a long time.  In particular, numbers over 5000.")
+
+    still_playing = True
+    while still_playing:
+        print("")
+        n = int(input("How many rolls? "))
+
+        # Roll the dice n times
+        for _ in range(n):
+            die1 = random.randint(1, 6)
+            die2 = random.randint(1, 6)
+            roll_total = die1 + die2
+            freq[roll_total] += 1
+
+        # Display final results
+        print("\nTotal Spots   Number of Times")
+        for i in range(2, 13):
+            print(" %-14d%d" % (i, freq[i]))
+
+        # Keep playing?
+        print("")
+        response = input("Try again? ")
+        if len(response) > 0 and response.upper()[0] == "Y":
+            # Clear out the frequency list
+            freq = [0] * 13
+        else:
+            # Exit the game loop
+            still_playing = False
 
 
-# Display intro text
-print("\n                   Dice")
-print("Creative Computing  Morristown, New Jersey")
-print("\n\n")
-# "Danny Freidus"
-print("This program simulates the rolling of a")
-print("pair of dice.")
-print("You enter the number of times you want the computer to")
-print("'roll' the dice.   Watch out, very large numbers take")
-print("a long time.  In particular, numbers over 5000.")
-
-still_playing = True
-while still_playing:
-    print("")
-    n = int(input("How many rolls? "))
-
-    # Roll the dice n times
-    for _ in range(n):
-        die1 = random.randint(1, 6)
-        die2 = random.randint(1, 6)
-        roll_total = die1 + die2
-        freq[roll_total] += 1
-
-    # Display final results
-    print("\nTotal Spots   Number of Times")
-    for i in range(2, 13):
-        print(" %-14d%d" % (i, freq[i]))
-
-    # Keep playing?
-    print("")
-    response = input("Try again? ")
-    if len(response) > 0 and response.upper()[0] == "Y":
-        # Clear out the frequency list
-        freq = [0] * 13
-    else:
-        # Exit the game loop
-        still_playing = False
-
+if __name__ == "__main__":
+    main()
 
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