instantiation

问题 I've got a highly complex class : class C: pass And I've got this test code : for j in range(10): c = C() print c Which gives : <__main__.C instance at 0x7f7336a6cb00> <__main__.C instance at 0x7f7336a6cab8> <__main__.C instance at 0x7f7336a6cb00> <__main__.C instance at 0x7f7336a6cab8> <__main__.C instance at 0x7f7336a6cb00> <__main__.C instance at 0x7f7336a6cab8> <__main__.C instance at 0x7f7336a6cb00> <__main__.C instance at 0x7f7336a6cab8> <__main__.C instance at 0x7f7336a6cb00> <__main__

问题 Within the C++ language, many will come across various design patterns that have a designated name in which we would call an Idiom, such as SFINAE , RAII , CRTP , Polymorphism , etc... Consider this following code snippet in its most basic form... template<typename T> auto make_object = [](T val) { class Foo { public: Foo(T val) : value_{val} {} T value() const { return value_; } private: T value_; }; Foo foo(val); return foo; }; // in some other code block, scope, or translation int main() {

问题 So while trying to understand abstract classes, there is still one thing I am confused on. When do you ever want to declare an object type of its abstract class. For example public abstract class GameObject { public abstract void draw(); public static void main(String[] args) { GameObject player = new Player(); Menu menu = new Menu(); } } public class Player extends GameObject { override public void draw() { // Something } } public class Menu extends GameObject { override public void draw() {

问题 So while trying to understand abstract classes, there is still one thing I am confused on. When do you ever want to declare an object type of its abstract class. For example public abstract class GameObject { public abstract void draw(); public static void main(String[] args) { GameObject player = new Player(); Menu menu = new Menu(); } } public class Player extends GameObject { override public void draw() { // Something } } public class Menu extends GameObject { override public void draw() {

问题 I'm following a tutorial where a ViewModel extends an abstract class in order to use coroutines, this is the class that extends: abstract class BaseViewModel(application: Application) : AndroidViewModel(application), CoroutineScope { private val job = Job() override val coroutineContext: CoroutineContext get() = job + Dispatchers.Main override fun onCleared() { super.onCleared() job.cancel() }} And this is the ViewModel: class ViewModel(application: Application) : BaseViewModel(application) {

问题 Class Example: $(document).ready(function(){ var $ = function(id) { return document.getElementById(id); } class someClass { constructor() { ... } someMethod() { ... } } ... // rest of examples within this scope }); So far I am able to create an instance of the class object when the window loads and then calling a method of that class on a button click event while also binding this : var obj = new someClass() $('startButton').onclick = obj.someMethod.bind(obj) All works fine and well until I

问题 I am developing a class. The class-level data it will need is going to be relatively complex. To save typing and minimize mistakes, I would like to define a good bit of this data through functions. Also, I would like to make this data available to the user even if they aren't ready to instantiate the class. So, I wonder, is there a way to get these functions to run automatically as soon as the class is defined? As an example, I want something like import numpy as np def class foo: @this

问题 Is there an easy way to see whether a class has been instantiated in a translation unit? An exercise from C++ Primer asks for each labelled statement, whether an instantiation happens: template <typename T> class Stack { }; void f1(Stack<char>); // (a) class Exercise { Stack<double> &rsd; // (b) Stack<int> si; // (c) }; int main() { Stack<char> *sc; // (d) f1(*sc); // (e) int iObj = sizeof(Stack< string >); // (f) } I'm not sure how I could actually check my answers for these. I thought maybe

问题 Is there an easy way to see whether a class has been instantiated in a translation unit? An exercise from C++ Primer asks for each labelled statement, whether an instantiation happens: template <typename T> class Stack { }; void f1(Stack<char>); // (a) class Exercise { Stack<double> &rsd; // (b) Stack<int> si; // (c) }; int main() { Stack<char> *sc; // (d) f1(*sc); // (e) int iObj = sizeof(Stack< string >); // (f) } I'm not sure how I could actually check my answers for these. I thought maybe

问题 This question already has answers here : Closed 9 years ago . Possible Duplicate: Why are C# 3.0 object initializer constructor parentheses optional? What is the difference between instatiating an object by using classInstance = new Class() { prop1 = "", prop2 = "" }; and classInstance = new Class { prop1 = "", prop2 = "" }; 回答1: Nothing. The second is just a short-cut for the first. The first allows you to include arguments to a constructor. So, you can't use the short-cut if the class doesn