The order you refer in your question is not the “order of calling base constructor”. In fact, you can’t call a constructor. Constructors are not callable by the user. Only compiler can call constructors. What you can do is to specify initializers. In this case (constructor initializer list) you are specifying initializers for subobjects of … Read more
I hat the same problems with a library of mine providing “plugin”-functionality… I got it finally working… Here was my problem: I had one main assembly using plugins, one assembly with the plugin (Plugin.dll) AND (important) another assembly providing the plugin-functionality (Library.dll). The Plugin.dll referenced the main assembly (in order to be able to extend … Read more
I smell a code smell here. It is my opinion that you should only inherit a base class if you’re implementing all of the functionality of that base class. What you’re doing doesn’t really represent object oriented principles properly. Thus, if you want to inherit from your base, you should be implementing Name, otherwise you’ve … Read more
This is simply how C# is going to work. The constructors for each type in the type hierarchy will be called in the order of Most Base -> Most Derived. So in your particular instance, it calls Person(), and then Customer() in the constructor orders. The reason why you need to sometimes use the base … Read more
The destructor of A will run when its lifetime is over. If you want its memory to be freed and the destructor run, you have to delete it if it was allocated on the heap. If it was allocated on the stack this happens automatically (i.e. when it goes out of scope; see RAII). If … Read more
If you are just adding behavior, and not depending on additional instance values, you can assign to the object’s __class__: from math import pi class Circle(object): def __init__(self, radius): self.radius = radius def area(self): return pi * self.radius**2 class CirclePlus(Circle): def diameter(self): return self.radius*2 def circumference(self): return self.radius*2*pi c = Circle(10) print c.radius print c.area() … Read more
David Joyner had the history, here is the reason. The problem when compiling B<T> is that its base class A<T> is unknown from the compiler, being a template class, so no way for the compiler to know any members from the base class. Earlier versions did some inference by actually parsing the base template class, … Read more
There are no good uses of a base controller class. Now hear me out. Asp.Net MVC, especially MVC 3 has tons of extensibility hooks that provide a more decoupled way to add functionality to all controllers. Since your controllers classes are very important and central to an application its really important to keep them light, … Read more
Let’s take your example of a Dog and a Cat class, and let’s illustrate using C#: Both a dog and a cat are animals, specifically, quadruped mammals (animals are waaay too general). Let us assume that you have an abstract class Mammal, for both of them: public abstract class Mammal This base class will probably … Read more
Use a Metaclass I would recommend Method #2, but you’re better off using a metaclass than a base class. Here is a sample implementation: class Singleton(type): _instances = {} def __call__(cls, *args, **kwargs): if cls not in cls._instances: cls._instances[cls] = super(Singleton, cls).__call__(*args, **kwargs) return cls._instances[cls] class Logger(object): __metaclass__ = Singleton Or in Python3 class Logger(metaclass=Singleton): … Read more