super

问题 I have read other questions which explain the difference between __init__ and __new__ but I just do not understand why in the following code with python 2 out: init and Python3: new init The sample code: class ExampleClass(): def __new__(cls): print ("new") return super().__new__(cls) def __init__(self): print ("init") example = ExampleClass() 回答1: To use __new__ in Python 2.x, the class should be new-style class (class derived from object ). And call to super() is different from that of

问题 This question, is a followup to this one. When using super() for multiple inheritance, the suggested approach was to use keyword arguments to pass remaining values up the call chain. When using the ABC module, is it good practice do the same in the super().__init__ method? The blog post, which the Python documentation about super() links to, doesn't mention anything about using **kwargs and the ABC module. It's focused on multiple inheritance with concrete classes. To rephrase my question,

问题 I'm trying to figure out how to use this._super when the Ember's object method is called from a callback. I know that I could assign var _super = this._super before the callback is called but I don't like it. I want to have the this object containing proper _super method inside the callback. My code is here: http://emberjs.jsbin.com/hasehija/6/edit. App.BaseMixin = Ember.Mixin.create({ init: function() { console.log("base"); } }); App.Utils = Ember.Object.extend({ callbackMethod: function

问题 I am following a tutorial online and the code is this: class Hands(list): def __init__(self, size=0, die_class=None, *args, **kwargs): if not die_class: raise ValueError("You must provide a die class") super().__init__() for _ in range(size): self.append(die_class()) It basically models a player with a number of dice ( size ) and what dice they are holding ( die_class ). My confusion is why do we need to call super().__init__ ? I tried running the code without it and it worked fine! Why is

问题 This question already has answers here : Forward an invocation of a variadic function in C (10 answers) Closed 5 years ago . I need to implement a universal C function which will invoke super 's implementation and return the value. I will inject this function to a target class at runtime. The number of arguments of the target selector could be any number, and would be known only at runtime. I implement a C function as following, but I don't know how to invoke the super 's implementation with

问题 Given is the following code: function two() { return "success"; } function one() { two(); return "fail"; } If you test the code by calling function one(), you will always get "fail". The question is, how can I return "success" in function one() by only calling function two()? Is that even possible? Regards 回答1: You can't make a function return from the function that called it in Javascript (or many other languages, afaik). You need logic in one() to do it. E.g.: function one() { return two()

问题 Please explain public class Contact { private String contactId; private String firstName; private String lastName; private String email; private String phoneNumber; public Contact(String contactId,String firstName, String lastName, String email, String phoneNumber) { super(); //what does standalone super() define? With no args here? this.firstName = firstName; this.lastName = lastName; //when is this used?, when more than one args to be entered? this.email = email; this.phoneNumber =

问题 In Python 3.x, super() can be called without arguments: class A(object): def x(self): print("Hey now") class B(A): def x(self): super().x() >>> B().x() Hey now In order to make this work, some compile-time magic is performed, one consequence of which is that the following code (which rebinds super to super_ ) fails: super_ = super class A(object): def x(self): print("No flipping") class B(A): def x(self): super_().x() >>> B().x() Traceback (most recent call last): File "<stdin>", line 1, in

问题 Simple question. I made a class called Tester1 which extends another called Tester2. Tester2 contains a public string called 'ABC'. Here is Tester1: public class Tester1 extends Tester2 { public Tester1() { ABC = "Hello"; } } If I instead change line 5 to super.ABC = "Hello"; am I still doing the exact same thing? 回答1: Yes. There's only one ABC variable within your object. But please don't make fields public in the first place. Fields should pretty much always be private. If you declared a

问题 I have seen some Apple examples that do call [super viewDidUnload]; and some that don't. I read an article (a few months ago so I dont recall the url) that said calling [super viewDidUnload]; was unnecessary but it didn't explain beyond that. Is there a definitive reason why or why not to tell super that the viewDidUnload ? And, (if it should be done) do I call super before setting all my properties to nil , after, or does it matter? - (void)viewDidUnload { // Is this necessary? // [super