update from Atlas

metaprog/blackknight.py

@@ -0,0 +1,48 @@
+"""
+This class is inspired by the Black Knight scene in the movie
+"Monty Python and the Holy Grail", where King Arthur fights the
+Black Knight, slicing off his arms and legs, but the knight
+refuses to concede defeat.
+
+# BEGIN BLACK_KNIGHT_DEMO
+    >>> knight = BlackKnight()
+    >>> knight.member
+    next member is:
+    'an arm'
+    >>> del knight.member
+    BLACK KNIGHT (loses an arm)
+    -- 'Tis but a scratch.
+    >>> del knight.member
+    BLACK KNIGHT (loses another arm)
+    -- It's just a flesh wound.
+    >>> del knight.member
+    BLACK KNIGHT (loses a leg)
+    -- I'm invincible!
+    >>> del knight.member
+    BLACK KNIGHT (loses another leg)
+    -- All right, we'll call it a draw.
+
+# END BLACK_KNIGHT_DEMO
+"""
+
+# BEGIN BLACK_KNIGHT
+class BlackKnight:
+
+    def __init__(self):
+        self.members = ['an arm', 'another arm',
+                        'a leg', 'another leg']
+        self.phrases = ["'Tis but a scratch.",
+                        "It's just a flesh wound.",
+                        "I'm invincible!",
+                        "All right, we'll call it a draw."]
+
+    @property
+    def member(self):
+        print('next member is:')
+        return self.members[0]
+
+    @member.deleter
+    def member(self):
+        text = 'BLACK KNIGHT (loses {})\n-- {}'
+        print(text.format(self.members.pop(0), self.phrases.pop(0)))
+# END BLACK_KNIGHT