constructor
How much work should the constructor for an HTML parsing class do?
I normally follow one easy principle: Everything that is mandatory for the correct existence and behavior of the class instance should be passed and done into the constructor. Every other activity is done by other methods. The constructor should never: use other methods of the class with the purpose of using overriding behavior act on … Read more
Why is the copy-constructor argument const?
You’ve gotten answers that mention ensuring that the ctor can’t change what’s being copied — and they’re right, putting the const there does have that effect. More important, however, is that a temporary object cannot bind to a non-const reference. The copy ctor must take a reference to a const object to be able to … Read more
How does multiple inheritance work with the super() and different __init__() arguments?
For question 2, you need to call super in each class: class First(object): def __init__(self): super(First, self).__init__() print “first” class Second(object): def __init__(self): super(Second, self).__init__() print “second” class Third(First, Second): def __init__(self): super(Third, self).__init__() print “that’s it” For question 3, that can’t be done, your method needs to have the same signature. But you could … Read more
Calling a method in a Javascript Constructor and Accessing Its Variables
Yes, it is possible, when your constructor function executes, the this value has already the [[Prototype]] internal property pointing to the ValidateFields.prototype object. Now, by looking at the your edit, the errArray variable is not available in the scope of the CreateErrorList method, since it is bound only to the scope of the constructor itself. … Read more
What does the ‘new’ keyword actually do in Java, and should I avoid creating new objects?
Yes, if you called myMethod() 10 times it will create 10 unique and separate objects. The new keyword does exactly what it says on the tin, it creates a brand new object, irrespective of whether one already exists. It creates a new object and stuffs the reference to that object inside the variable it has … Read more
Why can’t we initialize class members at their declaration?
The initialization of non-static members could not be done like this prior to C++11. If you compile with a C++11 compiler, it should happily accept the code you have given. I imagine that the reason for not allowing it in the first place is because a data member declaration is not a definition. There is … Read more
Why does removing ‘const’ from the constructor parameter stop the class from being instantiated?
If const is there, and What<int> happens to have a constructor taking The, that would allow Heck(const What<int> &) to be used (because a const reference can bind to a temporary produced by such constructor). Checking for that constructor of What<int> requires instantiating the What<int> template. If there is no const, no implementation of What<int> … Read more
What is the difference between implicit constructors and default constructors?
The terms default and implicit, when talking about a constructor have the following meaning: default constructor is a constructor that can be called with no arguments. It either takes no arguments or has default values for each of the arguments taken. implicit constructor is a term commonly used to talk about two different concepts in … Read more
What is the difference between initialization and assignment in a constructor?
What might go wrong if we perform assignment instead of initialization? Some class types (and also references and const objects) can’t be assigned; some can’t be default-initialised; some might be more expensive to default-initialise and reassign than to initialise directly. Doesn’t the compiler internally performs assignment in case of test1() constructor? If no then how … Read more