Using Component (Declaring Namespace) in ASP.NET - Part 6


Introduction

Namespace enables us to group logically related classes. We are not required to provide a class with a namespace. To this point, all the components that we have created have been members of the global namespace. However, several advantages result from grouping components into namespaces.

First, namespaces prevent naming collisions. If two companies produce a component with the same name, then namespaces provide you with a method of distinguishing the components.

Second, namespaces make it easier to understand the purpose of a class. If we group all your data access components into a DataAccess namespace and all your business logic components in a BusinessLogic namespace, then we can immediately understand the function of a particular class.

In an ASP.NET page, we import a namespace like this:

<%@ Import Namespace="System.Collections" %>

In a Visual Basic component, on the hand, we import a namespace like this:

Imports System.Collections

We can create your own custom namespaces and group our components into namespaces by using the Namespacestatement. Here is the example given below.


Class1.vb File Code

Imports Microsoft.VisualBasic

Namespace AspNetUnleashed.SampleCode

    Public Class Namespaced

        Public Function SaySomething() As String
            Return "Something"
        End Function

    End Class

End Namespace


Default.aspx File Code

<%@ Page Language="VB" AutoEventWireup="false" CodeFile="Default.aspx.vb" Inherits="_Default" %>
<%@ Import Namespace="System.Collections" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:Label ID="Label1" runat="server" Text=""></asp:Label>
    </div>
    </form>
</body>
</html>


Default.aspx.vb File Code

Imports System.Collections

Partial Class _Default
    Inherits System.Web.UI.Page

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        Dim x As New AspNetUnleashed.SampleCode.Namespaced()
        Label1.Text = x.SaySomething()
    End Sub
End Class


In above example code we use the Namespace statement to group the Namespaced component into theAspUnleashed.SampleCode namespace. Components in different files can share the same namespace, and different components in the same file can occupy different namespaces.

Note: Continue in Next Part.

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