2016-12-08 | Paul Boddie | raw annotate files changeset graph | Ensure that base classes provide the attributes they use. Added tests demonstrating the use of attributes in base classes that are not necessarily defined in those classes or in some subclasses. |
1 class C: 2 def f(self): 3 return 1 4 5 def g(self): 6 return self.f() 7 8 class D(C): 9 pass 10 11 def f(): 12 return 2 13 14 c = C() 15 d = D() 16 17 # Invoke a method that calls the default version of f. 18 19 print c.g() # 1 20 print d.g() # 1 21 22 # Replace f in C and invoke the method again. For C, f will have changed, 23 # but for D, f will retain its original value. 24 25 C.f = f 26 27 print c.g() # 2 28 print d.g() # 1