ARTICLE

Creation of objects using Late-Binding technique

Posted by Santhosh Veeraraman in Articles | Visual Basic 2010 on April 11, 2008

Tags: factory method, factory pattern, instantiation, late binding, object, object creation

This article will explain how we can create objects in runtime, using late binding technique. Especially for a situation where you will come to know the class name only in runtime.

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Reader Level: Intermediate

Introduction

This article will explain how we can create objects in runtime, using late binding technique.

Late-Binding

Assume you are in a situation where you want to create object of a class only in runtime. Say for example, the class name is known to you only when you read it from an xml configuration file.

We can't instantiate it, because of the fact that we do not know which class has to be used. Late-binding technique will give you a hand in such kind of difficult situation.

Factory Method

We are using a factory method in this example, which will do the job for us. It will get the class name as parameter, create the object and give it back to you.

Code:

Imports System

Imports EtchingFormExceptions

''' <summary>

''' Factory Class

''' </summary>

Public NotInheritable Class Factory

Private Sub New()

End Sub
' This is a factory method that returns the required object

' using late binding.(i.e. the class is available only in runtime)

Public Shared Function GetEmployee(ByVal Classname As String) As Employee

Dim EmployeeObject As Employee

Try

' Set this as a rule. You have to pass Namespace.Classname

Dim FullName As String = "MyProjectNameSpace." + Classname

Dim t As Type = Type.[GetType](FullName)

' Create instance using Activator class.

Dim oTObject As Object = Activator.CreateInstance(t)

' Type cast it to our employee.

EmployeeObject = DirectCast(oTObject, Employee)

Catch generatedExceptionName As Exception

Throw New ClassNotFoundException()

End Try

Return EmployeeObject

End Function

End Class

NOTE: THIS ARTICLE IS CONVERTED FROM C# TO VB.NET USING A CONVERSION TOOL. ORIGINAL ARTICLE CAN BE FOUND ON C# Corner (http://www.c-sharpcorner.com/).