constructor

问题 I want to inject a MenuStrip Item or create a new one if it doesn't exists (but this is a different question) from the base constructor , the logic is the following: public class LocalizedForm : Form { public LocalizedForm() { Shown += (sender, e) => { MenuStrip menu = null; if (HasValidMenu(out menu)) LanguageManager.AttachMenu(menu); //Language Manager will inject MenuStripItems to the passed MenuStrip }; } protected bool HasValidMenu(out MenuStrip menu) { try { menu = Controls.OfType

问题 I want to process the variable and set the message but it is not possible as I am only allowed to call the super constructor at the first line only.Is there a way so that I can can set the exception message without calling the super constructor. 回答1: You are not Forced to call súper constructor always, bit if you do it, must be at the first line. In this case, use an init block which runs before constructor. 回答2: The message part of the exception is immutable and only able to set it during

问题 I have this domain: public class GenClass<T> { } public class Type1 { } public class Type2 { } public class GenType1 : GenClass<Type1> { } public class GenType2 : GenClass<Type1> { } public class GenType3 : GenClass<Type2> { } public class GenType4 : GenClass<string> { } public class GenType5 : GenClass<int> { } and this logic: public class SomeClass { public void Add<T>(GenClass<T> t) { } } and this consumer: public class Consumer { public void Method() { var some = new SomeClass(); some.Add

问题 I have created the following type using implicit type construction: open System type Matrix(sourceMatrix:double[,]) = let rows = sourceMatrix.GetUpperBound(0) + 1 let cols = sourceMatrix.GetUpperBound(1) + 1 let matrix = Array2D.zeroCreate<double> rows cols do for i in 0 .. rows - 1 do for j in 0 .. cols - 1 do matrix.[i,j] <- sourceMatrix.[i,j] //Properties ///The number of Rows in this Matrix. member this.Rows = rows ///The number of Columns in this Matrix. member this.Cols = cols //

问题 Are there any details on whether or not an object is cleaned up using finalize() if that object's constructor thew an exception. When this method is called is notoriously ill defined. According to the manual: The Java programming language does not guarantee which thread will invoke the finalize method for any given object. It is guaranteed, however, that the thread that invokes finalize will not be holding any user-visible synchronization locks when finalize is invoked. If an uncaught

问题 Yes, I know dependencies should be passed to the constructor. I'm not asking about coding styles or do's and dont's. Many of the classes in my application are tied to an instance of a database driver class. For this I've created an abstract Factory class using PHP's late static binding. The only member of this class is a property to hold the driver's reference. It looks like this: abstract class Factory { static private $__instances; static private $__default_driver; protected $_driver;

问题 I'm attempting to implement an example I found on JavaScript inheritance, and the child object does not seem to be constructing as expected. In the example below, creating the jill instance does not return a Jill object and the methods from the child or parent cannot be called. var Person = function() { this.name = "unnamed"; } Person.prototype.sayName = function() { console.log("My name is " + this.name); } var Jill = function() { var jill = function() { Person.call(this); this.name = "Jill"

问题 I get an error when dynamically creating an array of a (transaction) object. The error output says:"no matching function for call to 'Transaction::Transaction()' This is part of an assignment and we are not allowed to use a default constructor. From what I gather an array automatically assigns values to each of its indexed address when it's created and as no default constructor is made for Transaction, it cannot do this without values. Please help me see what I could do to fix this error.

问题 I am reading "Accelerated C++" by Andrew Koenig and Barbara E. Moo, and I'm at the chapter about constructors (5.1). They mention here that We said that constructors exist to ensure that objects are created with their data members in a sensible state. In general, this design goal means that every constructor should initialize every data member. The need to give members a value is especially critical for members of built-in type. ... Although we explicityly initialized only midterm and final ,

问题 I've done quite a bit of research on the new c++11 rvalue and carried over lvalue. Here is a sample of what I have found and read: what-does-t-double-ampersand-mean-in-c11 how-stdthread-constructor-detects-rvalue-reference stdthread-and-rvalue-reference I have also briefed myself on rvalue references Move_Semantics rvalue_references A Proposal to Add an Rvalue Reference to the C++ Language Specifically, regarding the std::thread constructor, I found how-to-create-a-thread-inside-a-class