abstract

According to the PHP manual , a class like this: abstract class Example {} cannot be instantiated. If I need a class without instance, e.g. for a registry pattern: class Registry {} // and later: echo Registry::$someValue; would it be considered good style to simply declare the class as abstract? If not, what are the advantages of hiding the constructor as protected method compared to an abstract class? Rationale for asking: As far as I see it, it could a bit of feature abuse, since the manual refers to abstract classes more as like blueprints for later classes with instantiation possibility.

I have an abstract base controller which has a constructor I hoped would be populated by autofac when the controllers were built. public abstract class BaseController : Controller { protected ILogger { get; private set; } protected BaseController() { } protected BaseController(ILogger logger) { Logger = logger; } } This doesnt seem to work when I derive a controller from it. I can only get this to work when I explicitly call the constructor explicitly from the controller. Is this the correct way to do this? public class PublicController : BaseController { public PublicController() { } public

What are the advantages and disadvantages of each of these? interface methods virtual methods abstract methods When one should choose what? What are the points one should keep in mind when making this decision? Virtual and abstract are almost the same. A virtual method has an implementation in the base class that can optionally be overridden, while an abstract method hasn't and must be overridden in a child class. Otherwise they are the same. Choosing between them depends on the situation. If you got a base implementation, you use virtual. If you don't, and you need every descendant to

What is the difference between sealed abstract and abstract Scala class? The difference is that all subclasses of a sealed class (whether it's abstract or not) must be in the same file as the sealed class. Daniel C. Sobral As answered , all directly inheriting subclasses of a sealed class (abstract or not) must be in the same file. A practical consequence of this is that the compiler can warn if the pattern match is incomplete. For instance: sealed abstract class Tree case class Node(left: Tree, right: Tree) extends Tree case class Leaf[T](value: T) extends Tree case object Empty extends Tree

I have a base class with the following (trimmed for brevity) declaration: public abstract class MyBaseClass { public int RecordId { get; private set; } public string ObjectName { get; set; } public abstract string Status { get; set; } public GetMyObject(int id) { MyObject myObject = context.GetObjectById(id); this.RecordId = myObject.RecordId; this.ObjectName = myObject.ObjectName; this.Status = myObject.Status } } Which is used by the following class: public class MySpecificClass : MyBaseClass { public override string Status { get { if(this.Status == "something") return "some status"; else

Possible Duplicate: Interface vs Abstract Class (general OO) When to use abstract class or interface? Can you provided implementations on a abstract class? what's the difference between these two? and when will I know when will I know to use them? This pages gives a good comparison: http://download.oracle.com/javase/tutorial/java/IandI/abstract.html . You could have found it with a very quick google search. Interface is used for defining a contract. Abstract classes are used for defining some methods which are common to all descendants and possibly some methods which will differ(they will be

So I have two classes: Property and Houses . Property is the abstract super class and Houses is its subclass. Here is the code for Property public abstract class Property{ String pCode; double value; int year; public Property(String pCode, double value , int year){ this.pCode = pCode; this.value = value; this.year = year; } public Property(){ pCode = ""; value = 0; year = 0; } public abstract void depreciation(); //Accessors private String getCode(){ return pCode; } private double getValue(){ return value; } private int getYear(){ return year; } //Mutators private void setCode(String newCode){