constructor

问题 I have the following code: #include <iostream> using namespace std; int foo() { throw 1; } struct A { int a; public: A() try : a(foo()) { cout << "Constructor A\n"; } catch(...) { cout << "Catched in A\n"; } }; struct B : A { B() { cout << "Constructor B\n"; ::foo(); } catch(...) { cout << "Catched in B\n"; } void foo() { } catch(...) { cout << "Catched in foo\n"; } }; int main () try { B b; return 0; } catch (...) { cout << "Catched in main\n"; } It outputs: Catched in A Catched in main Why

问题 I've found a task on some Java programming competition. One must create class Sentence with only one argument 'text' and only one constructor. Here's sample test code : Sentence s1=new Sentence("only","CAT"), s2=new Sentence("and", 2, "mice"), s3=new Sentence(s1,s2,"completely","alone"), s4=new Sentence(s3, "on the ", new Integer(32), "th street"); System.out.println(s1); Only cat. System.out.println(s2); Only cat and 2 mice. System.out.println(s3); Only cat and 2 mice completely alone.

问题 This question already has an answer here : Can't seem to use Interfaces with properties in VBA and I can't work out why (1 answer) Closed 2 years ago . I am just getting started using classes in VBA and I'm following the "Inheritance by construction" method outlined here. My example uses a simple class that contains a value (as a variant) and a value type (as a string). I created a subclass in which value type is set to string in the constructor. Here is my code: Interface Class (IVal) 'IVal

问题 I have all the class definitions in a header file: ModelModule.h. I have provided the sample code for that file below where I have given the declaration of 2 classes and its member functions: #pragma once #if !defined( MODELMODULE_H ) #define MODELMODULE_H //Required header files class CModelModule; class COrdProbitMM; class CModelModule // virtual base class for all types of modeling modules { friend class CSimCoordinator; friend class CHouseholdCoordinator; friend class CGenericHousehold;

问题 So here is my problem. I have a class called Login that will be used for logging in and creating new log in accounts. I've created a Login constructor that takes no arguments public Login() { _gloID = 0; _Username = null; _Password = null; _Note = null; _Active = false; _Status = null; _gvoID = 0; _DateModified = new DateTime(1901, 1, 1); _ModifiedBy = 0; } I've also created a Login constructor that takes two arguments. This constructor takes the username and password and then gathers the

问题 What's the best practice for calling a constructor of a class in scala 2.10 (M4+) ? 回答1: Answering my own question: Calling the constructor is different than invoking a method. Here's the right way to do it in scala 2.10 import reflect.runtime.universe._ import reflect.runtime.currentMirror val typ = typeOf[Range] val constructor = typ.members.find(_.kind == "constructor").get.asMethodSymbol currentMirror reflectClass typ.typeSymbol.asClassSymbol reflectConstructor constructor apply (1,10,1)

问题 In Java, constructors cannot be recursive. Compile time error: "recursive constructor invocation". Let's assume that we did not have this restriction. Things to keep in mind: The return type of a constructor is void. Since it is a void method you can't harness the complete power of recursion. A constructor can invoke itself (or any other constructor) using this(). But a "call to this must be first statement in constructor" We could use non local data between consecutive calls to still have

问题 In Java, constructors cannot be recursive. Compile time error: "recursive constructor invocation". Let's assume that we did not have this restriction. Things to keep in mind: The return type of a constructor is void. Since it is a void method you can't harness the complete power of recursion. A constructor can invoke itself (or any other constructor) using this(). But a "call to this must be first statement in constructor" We could use non local data between consecutive calls to still have

问题 I've been using C# for a long time and now I need to do something in Java. Is there something like C#'s struct automatic constructor in java ? What I mean is In C# struct MyStruct { public int i; } class Program { void SomeMethod() { MyStruct mStruct; // Automatic constructor was invoked; This line is same as MyStruct mStruct = new MyStruct(); mStruct.i = 5; // mStruct is not null and can i can be assigned } } Is it possible to force java to use default constructor on declaration ? 回答1: No -

问题 I have a class with overloaded constructors, like this: @Component public class MyClass { private ClassA myMemberA; private ClassA myMemberB; @Autowire public MyClass(@Qualifier ("qualifierA") ClassA objectA, ClassA objectB) { myMemberA = objectA; myMemberB = objectB; } @Autowire public MyClass(ClassA objectA) { myMemberA = objectA; } } Basically, one constructor has two arguments of ClassA , and one constructor has just one argument. I have two beans of type ClassA defined. I would like to