Calling Master Functions Through A Contract

Calling master functions and properties are a decade old question and the usual way is to define the master type in the content page i.e <%@ MasterType VirtualPath="~/Site.master" %> . This works well however it creates a strong dependency with one master type. How about changing the master dynamically from the content page. The situation gets worse. In that time, the masters have to be accessed to a common contract. So that whenever the master changes and sticks to the contract, the agreements never fails. The contract could be a super class, abstract class or an interface.

This sample code is about use of an interface. Have a simple interface in the App_code folder:

public interface ICommonMasterFunctions
{
    void setPageNumber(string number);
}

Have a label in the master page:

<div>
    <asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>
</div>

Implement the interface to all the masters required.

public partial class SiteMaster : System.Web.UI.MasterPage,ICommonMasterFunctions
{
    public void setPageNumber(string number)
    {
        Label1.Text = "You are on the page " + number.ToString();
    }
}

Now you can pass the page number from the content page:

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        ICommonMasterFunctions master = (ICommonMasterFunctions)this.Master;
        master.setPageNumber("5");
    }
}

As all the required masters agreed on this contract, changing the master doesn't need to change the code. This gives some flexibility.