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Virtual Override Abstract

Posted By:      Posted Date: August 23, 2010    Points: 0   Category :ASP.Net


can we have override, virtual and abstract with each other.

and  what are possible combinations of them which are possible........ ?????

can someone explain with an example ?????

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why Finalize() in Object is override not virtual?


Finalize() is override, why it's not virtual? what's difference between virtual and override for method in base class? Thanks

public class Object
    public Object();
    public virtual bool Equals(object obj);
    public static bool Equals(object objA, object objB);
    protected override void Finalize();
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Provide an interface for creating families of related or dependent objects without specifying their concrete classes

Abstract Factory Design Pattern (Sample in C# and VB .NET)

An abstract factory provides an interface for creating families of related objects without specifying their concrete classes. Sometimes one wants to construct an instance of one of a suite of classes, deciding between the classes at the time of instantiation. In order to avoid duplicating the decision making everywhere an instance is created, we need a mechanism for creating instances of related classes without necessarily knowing which will be instantiated.

Abstract Factory Pattern-Creational Patterns

The Factory pattern allowed us to decouple our client from an object which it uses. The Abstract Factory pattern extends this idea to manage separate families of objects.

A runtime selection, or configuration option, in our client could decide which family of objects is to be used. The Abstract Factory pattern allows us to write generic code to instantiate and use the family objects regardless of which family is chosen at runtime. The pattern also helps us enforce a rule where objects from just the chosen family are used uniformly by the client.

InterFaces and Abstract Classes

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abstract away the source of the connection string using a class with a static property.

ASP.NET provides a configuration system we can use to keep our applications flexible at runtime. In this article we will examine some tips and best practices for using the configuration system for the best results.

The element of a web.config file is a place to store connection strings, server names, file paths, and other miscellaneous settings needed by an application to perform work. The items inside appSettings are items that need to be configurable depending upon the environment, for instance, any database connection strings will change as you move your application from a testing and staging server into production.

Let's abstract away the source of the connection string using a class with a static property.

Virtual Path Problem


 I get the following error on last line below (working on remote host): 'E:\web\sfcascom\ls_admin/uploads/images/001.JPG' is not a valid virtual path,

Note that the slashes go in different directions

I've tried a number of things but nothing seems to work. Thanks-


Imports System.Drawing
Imports System.Drawing.Drawing2D
Imports System.Drawing.Imaging
Imports System.Web.UI.WebControls

Imports System.Drawing.Imaging.ImageCodecInfo
Partial Class Protected_imageupload
    Inherits System.Web.UI.Page
    Private Sub btnUpload_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnUpload.Click
        ' Initialize variables
        Dim sSavePath As String
        Dim sThumbExtension As String
        Dim intThumbWidth As Integer
        Dim intThumbHeight As Integer
        Dim sFilename As String = ""
        ' Set constant values
        'sSavePath = "images/"
        sSavePath = Server.MapPath("~/") + "ls_admin/uploads/images/"

        sThumbExtension = "_thumb"
        intThumbWidth = 160
        intThumbHeight = 120

        ' If file field isn?t empty
        If FilUpload.PostedFile IsNot Nothing Then
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Difference Btw Website vs Web application and Virtual directory in IIS 7


May i know what is the Differenc that they actually make in IIS7 .

Please tell me at a low level as i am still a novice in Asp.Net


Thanks in Advance.


Singleton Pattern and Abstract Class


I know what Singleton Pattern means and Abstract class means.

What I wanted to know was how would this apply to real world.

Could anyone give me any good example or simple explanation.

Say I have a simple website, why would I use any of the above if any.

Why would it simplify my architechture.

Thanks in advace. 

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