constructor

问题 So you have some function, say Gtk.Builder.get_object() , which returns some widget. In our case a Gtk.Window() . I have a subclass of Gtk.Window() which adds some signal handlers. class Window(Gtk.Window): Is it possible to use the widget returned by Gtk.Builder.get_object() to construct Window() ? I think it should be using __new__() or something, but I can't figure it out. 回答1: I think using __new__ is exactly what you want to be doing. If you can set the __class__ attribute of the

问题 I have this simple Shape class: Shape.h #import <Foundation/Foundation.h> @interface Shape : NSObject -(id)initWithColor:(UIColor *)color; +(instancetype)shapeWithColor:(UIColor *)color; @end and Shape.m #import "Shape.h" @interface Shape () @property (nonatomic, strong) UIColor *color; @end @implementation Shape -(id)init { return [self initWithColor:[UIColor whiteColor]]; } -(id)initWithColor:(UIColor *)color { self = [super init]; if (self) { _color = color; } return self; } +(instancetype

问题 i have this : class A { public : A(int i ) : m_S(i) { m_Pa = new Foo(*this) ; } private : int m_S ; Foo* m_Pa; } and derived class class B : public A { public : B() : A (242) { // here i like to override the A class m_Pa member but i don't know how to do it right } } 回答1: your m_Pa should be protected than you can call like: B() : A (242), m_Pa(12) { } or B() : A (242) { m_PA = 55 } or you should make a public or protected function which changes m_Pa class A { public : A(int i ) : m_S(i) { m

问题 Is there any way to create an instance of Derived but not call the constructor of Base ? open class Base(p: Int) class Derived(p: Int) : Base(p) 回答1: You actually can do it import sun.misc.Unsafe open class Base(p: Int){ init { println("Base") } } class Derived(p: Int) : Base(p){ init { println("Derived") } } fun main() { val unsafe = Unsafe::class.java.getDeclaredField("theUnsafe").apply { isAccessible = true }.get(null) as Unsafe val x = unsafe.allocateInstance(Derived::class.java) println(

问题 I've looked at all the following: Abstract constructor type in TypeScript How does `type Constructor<T> = Function & { prototype: T }` apply to Abstract constructor types in TypeScript? Abstract Constructor on Abstract Class in TypeScript The third is the closest to what I'm looking for, but (unfortunately) the answer was more for the specific issue and less for the question title. This is (in a simplified sense) what I'd like to be able to do: abstract class HasStringAsOnlyConstructorArg {

问题 I'm developing an application and a library using SourceryGpp lite for arm. I'm not using standard libs or default start files. So to call the global ctrs i'm doing to following code: ldr r0,=__ctors_init__ ldr r0,[r0] mov lr,pc bx r0 So the problem is that I'm defining some global instances in the static library, but the their ctors are never called by the above code. The weird thing is that the global ctors of the application are successfully called, anyone knows why? 回答1: This is a well

问题 I am trying to code an effective implementation of the following composite class: class composite{ vector<base_class *> Vec; //Other useful constants public: composite(vector<base_class*>); //Other useful operations... }; My question is about the constructor and instantiation of the class and in particular the object Vec. At the minute, I use the rather crude implementation outlined below. I the implementation to be memory efficient. I'm pretty much a newb with C++, so I'm not sure I have the

问题 I am creating a application form to view/change a tag from a software called InTouch. I added the dll as a reference and I would like to use the Read(string tagName ) fct in the IOM.InTouchDataAccess. VS does not see the fct Read when I write InTouchWrapper TagType = new read() . It only sees InTouchWrapper as I wrote in the code which gives me the error IOM.InTouchDataAccess.InTouchWrapper' does not contain a constructor that takes 0 arguments I don't understand why is this happening. I am

问题 New to Scala and no matter how many articles/tutorials I read (like these | three | ones) I can't seem to wrap my brain around how constructors work. Let's take three examples of a primary constructor here: // 1 class Fizz(buzz : Buzz) { ... } // 2 class Fizz (val buzz : Buzz) { ... } // 3 class Fizz (var buzz : Buzz) { ... } For each of these: Is a buzz property created? If so, is it public? Is it mutable? Is is static? Is a getter/setter created for it? Is a buzz field created? If so, is it

问题 Executing this peace of code class DefObject{ String a def b } def c = new DefObject(a:1, b:2); yields different results in Grails and in Groovy. Groovy assert c.a == 1 assert c.b == 2 Grails Domain Class assert c.a == 1 assert c.b == null How can I make Grails Domain to accept a value for b ? 回答1: This is because in domain classes, only "bindable" properties can be set via the map constructor. You can override whether a property is bindable or not (e.g. the id property isn't for security