Yes you should remove async. You should not force to use async to the class that implements it. There are other ways to return a Promise, not just async. Edit: Since it is not clear for some people why the async is not important. Here a couple of ways to return a promise: async function … Read more
You only imported ABCMeta from abc import ABCMeta Also import abstractmethod from abc import ABCMeta, abstractmethod and everything should be fine.
Absolutely correct. You should favor the protected constructor. EDIT: no the compiler doesn’t complain, but tools like FxCop (& Code Analysis) do. I believe there are some weird reflection tricks you can do with public constructors on abstract classes, but from a standpoint where you are merely providing base class functionality to other developers writing … Read more
abstract classes are not supported by actionscript 3. see http://joshblog.net/2007/08/19/enforcing-abstract-classes-at-runtime-in-actionscript-3/ the above reference also provides a kind of hackish workaround to create abstract classes in as3. Edit also see http://www.kirupa.com/forum/showpost.php?s=a765fcf791afe46c5cf4c26509925cf7&p=1892533&postcount=70 Edit 2 (In response to comment) Unfortunately, you’re stuck with the runtime error. One alternative would be to have a protected constructor…. except as3 doesn’t … Read more
A good example of real time found from here:- A concrete example of an abstract class would be a class called Animal. You see many animals in real life, but there are only kinds of animals. That is, you never look at something purple and furry and say “that is an animal and there is … Read more
Downside of extension methods: clients pre-C#3/VB9 won’t be able to use it as easily. That’s about it as far as I’m concerned – I think the interface-based approach is significantly nicer. You can then mock out your dependencies nicely, and everything is basically less tightly coupled. I’m not a huge fan of class inheritance unless … Read more
extern is unlikely to be something you want to use. It means that the method is implemented, but implemented externally – and typically used in interop scenarios where you’re defining a method implelemented in external code. abstract, on the other hand, means you’re defining the API for the method, but not providing an implementation. The … Read more
You could declare, and implement, a pure virtual destructor: class ShapeF { public: virtual ~ShapeF() = 0; … }; ShapeF::~ShapeF() {} It’s a tiny step from what you already have, and will prevent ShapeF from being instantiated directly. The derived classes won’t need to change.
Declaring a constructor on the same interface as the instance members doesn’t really make much sense — if you’re going to pass in a type dynamically to use in a constructor, it’s the static side of the class that would be restricted. What you would want to do is probably something like this: interface Colorable … Read more
Interesting – I’m not sure you can. However, if this is your real code, do you ever want to implement the non-generic GetEnumerator() in any way other than by calling the generic one? I’d do this: abstract class MyList<T> : IEnumerable<T> { public abstract IEnumerator<T> GetEnumerator(); IEnumerator IEnumerable.GetEnumerator() { return GetEnumerator(); } } That saves … Read more