ASP.NET Templated User Controls "Container" keyword

I'm working with Templated User Control's. In the final markup of the control, the data is being accessed by the Container keyword. I'm using the word 'keyword' freely, because I do not understand whether this is a keyword, or where the Container word is coming from. Below is an example from my book.

//Address User Control markup
<%@ Control Language="C#" AutoEventWireup="true"
CodeFile="AddressUcTemplated.ascx.cs" Inherits="AddressUcTemplated" %>
<asp:PlaceHolder runat="server"
ID="PlaceHolderAddressTemplate">
</asp:PlaceHolder>

--

//Address User Control code-behind
public partial class AddressUcTemplated :
System.Web.UI.UserControl
{
protected void Page_Init(object sender, EventArgs e)
{
//clear the controls from the placeholder
PlaceHolderAddressTemplate.Controls.Clear();
if (LayoutTemplate == null)
{
PlaceHolderAddressTemplate.Controls.Add(
new LiteralControl("No template defined."));
}
else
{
AddressUcContainer container = new
AddressUcContainer(this.Address);
this.LayoutTemplate.InstantiateIn(container);
//add the controls to the placeholder
PlaceHolderAddressTemplate.Controls.Add(container);
}
}
[PersistenceMode(PersistenceMode.InnerProperty)]
[TemplateContainer(typeof(AddressUcContainer))]
public ITemplate LayoutTemplate { get; set; }
public Address Address { get; set; }
}

--

//Naming Container Class
    public class AddressUcContainer : Control, INamingContainer
    {
    public AddressUcContainer(Address address)
    {
    this.Address = address;
    }
    public Address Address { get; set; }
    }

--

     //Page using the user control; the Container keyword is confusing me in the below //statement
...
<%@ Register src="AddressUcTemplated.ascx" tagname="AddressUcTemplated"
tagprefix="uc1" %>
        <uc1:AddressUcTemplated ID="AddressUcTemplated1"
        runat="server" AddressType="H开发者_JAVA技巧ome">
        <LayoutTemplate>
        <h1>Edit Home Address</h1>
        <table>
        <tr>
        <td>Address Line 1:</td>
        <td>
        <asp:TextBox ID="TextBoxAddress" runat="server"
        Text="<%#Container.Address.AddressLine1%>"></asp:TextBox>
        ...

My example code is as follows:

<asp:Repeater runat="server">
    <ItemTemplate><%# Container.DataItem %></ItemTemplate>
</asp:Repeater>

Intellisense states that Container is a field/variable of type RepeaterItem. The variable-part tells me that this is some special parsing, since it would most probably been a property if it was public stuff.

Anyway, my code is parsed into, amongst other, the following databinding code:

public void __DataBind__control4(object sender, EventArgs e) {
    var target = (DataBoundLiteralControl)sender;
    var Container = (RepeaterItem)target.BindingContainer;
    target.SetDataBoundString(0, Convert.ToString(Container.DataItem, CultureInfo.CurrentCulture));
}

<%# ... %> is a DataBoundLiteralControl, and Container is the variable that's exposed to intellisense. This also shows that there's a target variable, which does not show up in intellisense, but compiles without any problems. Note that this also gives you access to everything private in the generated class, like __fileDependencies.

<%# target %> works, while <%# dummy %> doesn't. And while at it, <%# __DataBind__control4(null, null) %> creates two compilation errors, 1) "The best overloaded method match for 'System.Convert.ToString(object, System.IFormatProvider)' has some invalid arguments" and 2) "Argument 1: cannot convert from 'void' to 'object'".

This looks like a simple case of whatever is written between <%# ... %> is placed in Convert.ToString(..., CultureInfo.CurrentCulture). It's probably more advanced, involving different ControlBuilders, TemplateParsers, and an ounce of magic, but I think my abstraction works well enough to understand this.