NSMutableArray is not a concrete class, it is just the abstract superclass of a class cluster. The documentation for NSMutableArray does have information about how to subclass, but also strongly advises you not to! Only subclass if you have a special need for actual storage. A class cluster means that the actual class will be … Read more
Class and instance methods live in the same namespace and you cannot reuse names like that; the last definition of id will win in that case. The class method will continue to work on instances however, there is no need to create a separate instance method; just use: class X: @classmethod def id(cls): return cls.__name__ … Read more
If AnInterface is Java, you can work with SAM conversion: val impl = AnInterface { inst, num -> //… } Otherwise, if the interface is Kotlin… interface AnInterface { fun doSmth(inst: MyClass, num: Int) } …you can use the object syntax for implementing it anonymously: val impl = object : AnInterface { override fun doSmth(inst:, … Read more
Abstract methods means there is no default implementation for it and an implementing class will provide the details. Essentially, you would have abstract class AbstractObject { public abstract void method(); } class ImplementingObject extends AbstractObject { public void method() { doSomething(); } } So, it’s exactly as the error states: your abstract method can not … Read more
You are looking for the __call__ method. Function objects have that method: >>> def foo(): pass … >>> foo.__call__ <method-wrapper ‘__call__’ of function object at 0x106aafd70> Not that the Python interpreter loop actually makes use of that method when encountering a Python function object; optimisations in the implementation jump straight to the contained bytecode in … Read more
Try the following: class Foo { function bar() { $static = !(isset($this) && $this instanceof self); } } Source: seancoates.com via Google
In Ruby 2.0 and later you can use Module#prepend: class Date prepend DateExtension end Original answer for older Ruby versions is below. The problem with include (as shown in the following diagram) is that methods of a class cannot be overridden by modules included in that class (solutions follow the diagram): Solutions Subclass Date just … Read more
The int version of bar is being called, because 10 is an int literal and the compiler will look for the method which closest matches the input variable(s). To call the long version, you’ll need to specify a long literal like so: foo.bar(10L); Here is a post by Eric Lippert on much more complicated versions … Read more
Here you can see that there are 2 public static void main (String args[]) in a single file with the name Test.java (specifically didn’t use the name of file as either of the 2 classes names) and the 2 classes are with the default access specifier. class Sum { int add(int a, int b) { … Read more
When you program in Objective-C you need to purge your mind of such things as virtual methods. You don’t call methods on Objective-C objects, you send messages to them. Objects either respond to messages or they don’t, but due to the dynamic binding, you can’t tell this until run time. Thus, you can declare a … Read more