Changeset 963

Timestamp:

07/03/11 20:07:47 (11 months ago)

Author:

hodgestar

Message:

Another MRO fiddling example.

Files:

• hodgestar/Talks/PythonMRO/custom_mro.py (modified) (4 diffs)

hodgestar/Talks/PythonMRO/custom_mro.py

@@ -1 @@
-#from types import Type
+import random
 
 
@@ -5 +5 @@
     def mro(cls):
         return cls.__dict__['mro']
+
+
+class RandomMRO(type):
+    def mro(cls):
+        sane_mro = type.mro(cls)[:-1]
+        random.shuffle(sane_mro)
+        sane_mro.append(object)
+        return sane_mro
 
 
@@ -26 +34 @@
 
 
+class D(object):
+    pass
+
+
+class E(D):
+    pass
+
+
+class F(E):
+    __metaclass__ = RandomMRO
+
+
 if __name__ == "__main__":
     c = C()
-    print "MRO:", C.__mro__
+    print "MRO C:", C.__mro__
     print "Bases:", C.__bases__  # just object
     print "Attributes present:", c.a, c.b, c.x, c.foo
@@ -35 +55 @@
     print "Instance B?", isinstance(c, B)  # True (odd?)
     print "Instance object?", isinstance(c, object)
+    print "----"
+    print
+
+    f = F()
+    print "MRO F:", F.__mro__
+    print "Expected:", "F, E, D, object"
+    print "----"
+    print