superclass

Suppose I have the class class A { protected: int x,y; double z,w; public: void foo(); void bar(); void baz(); }; defined and used in my code and the code of others. Now, I want to write some library which could very well operate on A's, but it's actually more general, and would be able to operate on: class B { protected: int y; double z; public: void bar(); }; and I do want my library to be general, so I define a B class and that's what its APIs take. I would like to be able to tell the compiler - not in the definition of A which I no longer control, but elsewhere, probably in the definition

For some reason, the super() method is not always behaving as expected, opting to return: TypeError('super(type, obj): obj must be an instance or subtype of type)' I understand what the error means . I do not understand why it is coming up as an error. Here's the snippet of code that is breaking. All objects in the system are new style objects. What's really interesting is that this error does not always show up. I don't know what's causing it. The super() method in Retrieval is passing the Retrieval class, and then itself as an object, which is, as far as I'm aware,exactly how super() is

Why object Class is a super class in java yesterday i had one interview and the interviewer asked me the questions. Because the Object class, in the java.lang package, sits at the top of the class hierarchy tree. Because it is just a definition. Actually sec 4.3.2 of jls8 said: The class Object is a superclass (§8.1.4) of all other classes. There is no more formal way to define Object class. Because all objects in Java inherited from Object class. So if you create your class for example MyObject , parent for this object will be Object class. It's mean that Object is super class for class

This question already has an answer here: Why call super() in a constructor? 5 answers I'm a Java beginner learning about Java compiler rules as below: If the class has no super class, extend it to Object class If the class has no constructor, add a default no-parameter constructor If the first line of the constructor is not "super()" or "this()", add "super()" to call the default constructor of the super class. I understand that all objects we create are derived from the super class Object. My question is what does the constructor in the Object class do when called? Edit: My question is about

I would like to test whether a class inherits from another class, but there doesn't seem to exist a method for that. class A end class B < A end B.is_a? A => false B.superclass == A => true A trivial implementation of what I want would be: class Class def is_subclass_of?(clazz) return true if superclass == clazz return false if self == Object superclass.is_subclass_of?(clazz) end end but I would expect this to exist already. Marcel Jackwerth Just use the < operator B < A # => true A < A # => false or use the <= operator B <= A # => true A <= A # => true Also available: B.ancestors.include? A

Today, I read the official doc of super . In which it mentioned multiple inheritance will be decided by the __mro__ attribute of a class. So I did a bit experiment, but its result surprised me. # CODE PART class GrandFather(object): def p(self): print "I'm old." class Father(GrandFather): def p(self): print "I'm male." class Mother(object): def p(self): print "I'm female." class Son(Father, Mother): def p(self): print "busy, busy, crwaling. " # EXPERIMENT PART In [1]: Son.__mro__ Out[1]: (__main__.Son, __main__.Father, __main__.GrandFather, __main__.Mother, object) In [2]: Father.__mro__ Out[2

According to the docs, super(cls, obj) returns a proxy object that delegates method calls to a parent or sibling class of type cls I understand why super() offers this functionality, but I need something slightly different: I need to create a proxy object that delegates methods calls (and attribute lookups) to class cls itself; and as in super , if cls doesn't implement the method/attribute, my proxy should continue looking in the MRO order (of the new not the original class). Is there any function I can write that achieves that? Example: class X: def act(): #... class Y: def act(): #... class

like in java I have: Class.getSuperClass().getDeclaredFields() how I can know and set private field from a superclass? I know this is strongly not recommended, but I am testing my application and I need simulate a wrong situation where the id is correct and the name not. But this Id is private. JaredPar Yes, it is possible to use reflection to set the value of a readonly field after the constructor has run var fi = this.GetType() .BaseType .GetField("_someField", BindingFlags.Instance | BindingFlags.NonPublic); fi.SetValue(this, 1); EDIT Updated to look in the direct parent type. This solution