While the type parameters of a generic method can be restricted by bounds, such as extends Foo & Bar, they are ultimately decided by the caller. When you call getFooBar(), the call site already knows what T is being resolved to. Often, these type parameters will be inferred by the compiler, which is why you … Read more
An interface is simply a base class that has no data members and only defines public abstract methods. For example, this would be an interface in C++: class IFrobbable { public: virtual void Frob() = 0; } Therefore when MI is available as a language feature you can “implement” interfaces by simply deriving from them … Read more
a.base1::start(); a.base2::start(); or if you want to use one specifically class derived:public base1,public base2 { public: using base1::start; };
super() is not broken — it just should not be considered the standard way of calling a method of the base class. This did not change with Python 3.x. The only thing that changed is that you don’t need to pass the arguments self, cls in the standard case that self is the first parameter … Read more
No, Extension methods can not act as implementation for an interface. Extensions methods are just syntactic sugar for a static method taking an instance of that class as the first parameter, thus not being a member of the specific class, which is a requirement for implementing an interface.
Member lookup rules are defined in Section 10.2/2 The following steps define the result of name lookup in a class scope, C. First, every declaration for the name in the class and in each of its base class sub-objects is considered. A member name f in one sub-object B hides a member name f in … Read more
You could do it with generics: public <T extends Appendable & Closeable> void spew(T t){ t.append(“Bleah!\n”); if (timeToClose()) t.close(); } Your syntax was almost right, actually.
I’ve never missed it once, not ever. Yes, it [MI] gets complicated, and yes, interfaces do a similar job in many ways – but that isn’t the biggest point: in the general sense, it simply isn’t needed most of the time. Even single inheritance is overused in many cases.
Actually, I have no good answer other than Java SHOULD have Multiple Inheritance. The whole point that interfaces should be able to replace the need for Multiple Inheritance is like the big lie that when repeated enough times becomes true. The argument is that Multiple Inheritance causes all these problems (la-di-dah), yet I keep hearing … Read more
Change your code to this and I think it’ll explain things (presumably super is looking at where, say, B is in the __mro__?): class A(object): def __init__(self): print “A init” print self.__class__.__mro__ class B(A): def __init__(self): print “B init” print self.__class__.__mro__ super(B, self).__init__() class C(A): def __init__(self): print “C init” print self.__class__.__mro__ super(C, self).__init__() class … Read more