constructor

问题 I know Crockford has a famous object function for inheritance in JavaScript: function object(o) { function F() {} F.prototype = o; return new F(); } But I am confused, after the line F.prototype = o , why he doesn't he reset the F.prototype 's constructor, like this: F.prototype.constructor = F Isn't that common practice? 回答1: Isn't that common practice? Only when your're creating subclasses (constructor functions with prototypes inheriting from other prototypes). But that's not the purpose

问题 I have a main class called Bar that calls the class Foo, and I think I put in a deep constructor correctly The purpose of a deep copy constructor is to copy the contents of one object to another object and changing the copied object shouldn't change the contents of the original, correct? My code does that, but I don't understand why when I set the original object variable, the copying object doesn't contain that set variable, it just contains the default constructor variable. public class Bar

问题 TLDR: How can you get the contents of a constructor/properties without actually knowing what it contains? Given the following: function f(args) { this.defaults { param1 : 100, param2 : 900; }; this.ranges { param1 : { min : 0, max : 500 }, param2 : { min : 0, max : 1000 }; }; } var myF = new f(); The defaults and ranges can be accessed through the myF.defaults.param1 and myF.ranges.param1.min calls. What if you do not know the name of the defaults or the ranges ? How can you get the names and

问题 I want to create a constructor object whose inheritance works as normal, but capture the constructor so I can manipulate the instance object. Using Proxy() almost solves this, but it seems to screw up the inheritance. Note the following example without a proxy: > const B = function() {} undefined > B.name 'B' > class C extends B {} [Function: C] > B.prototype == C.prototype.__proto__ true > var instance = new C() undefined > C.prototype == instance.__proto__ true > instance.__proto__ C {} Now

问题 I've read about class fromal parameters and the question then arises as to why the following code is ill-formed? class A : package org.gradle; public class A extends B.Inner{ public A(B s){ s.super(new B()); //error s.super(); //OK } } class B : package org.gradle; public class B{ public class Inner{ } } The key part of what was said is: The constructor of a non-private inner member class implicitly declares, as the first formal parameter, a variable representing the immediately enclosing

问题 on more than one occasion I felt the need to define class methods that get called in a manner similar to constructors or destructors. A specific example would be; in a program I had a very complex network of nodes of different types that depended mutually on each other in a very irregular fashion (The network did not resemble a tree at all). When a node needed to be destroyed, it started a complex chain of destructions in the network. Much like a spider web being torn apart, but more complex.

问题 Is there a way I can construct the following class in such a way that I can code the setting of Service and Values only once: public class MyClass { private readonly IService Service; public List<int> Values { get; set; } public int Value { get; set; } public MyClass(IService service, List<int> values) { Service = service; Values = values; Value = Values.FirstOrDefault(i => i == Service.GetDefaultValue()); } public MyClass(IService service, List<int> values, int value) { Service = service;

问题 I've read Passing pointer to derived class, to function that expects pointer to base class? but the answer doesn't seem applicable to my issue. I checked via Ideone that the following compiles, as it should: class Base { public: Base() {} virtual ~Base() {} }; class Derived : public Base { public: Derived() {} virtual ~Derived() {} }; class Manager { public: Manager(Base* b) {} ~Manager() {} private: Manager() {} }; int main() { Derived* d = new Derived; Manager* m = new Manager(d); return 0;

问题 How to pass the textfield from main class pri to CounterTask1 class. Below program is an example. Real program contains similar construction. In CounterTask1 class the textfield add with another string.If click print button it should print textfield in terminal. Advance Thanks. import java.io.*; import javax.swing.*; import java.awt.event.*; import javax.swing.SwingWorker; import java.util.List; public class pri { JFrame Frame1 = new JFrame(); JLabel SourceLabel1 = new JLabel("Source Name");

问题 Calling virtual methods in C++ is prohibited, however there are a few situations, where it might be very useful. Consider the following situation - pair of Parent and Child classes. Parent constructor requires a Child class to be instantiated, because it has to initialize it in a special way. Both Parent and Child may be derived, such that DerivedParent uses DerivedChild. There's a problem, however - because in Parent::ctor call from DerivedParent::ctor, base class should have an instance of