Generate an immutable data structure with a T4 template

Immutable.tt

<#@ template language="C#" #>
<#@ assembly name="System.Core" #>
<#@ import namespace="System.Linq" #>
<#@ import namespace="System.Text" #>
<#@ import namespace="System.Collections.Generic" #>
<#

var name = "Badge";
var fields = new Dictionary<string, string>{
	{ "UserId",  "string" },
	{ "BadgeId", "int?" },
	{ "StartDate", "DateTime" },
	{ "EndDate", "DateTime" }
};

var isFirst = true;
#>
using System;

namespace Stuff
{
	class <#= name #>
	{
<# foreach (var pair in fields) { #>
		public <#= pair.Value #> <#= pair.Key #> { get; }
<# } #>

		public <#= name #> (<# foreach (var pair in fields) { #><#= isFirst ? "" : ", "#><# isFirst = false; #><#= pair.Value #> <#= pair.Key #><# } #>)
		{
<# foreach (var pair in fields) { #>
			this.<#= pair.Key #> = <#= pair.Key #>;
<# } #>
		}

<# foreach (var pair in fields) { 
	isFirst = true;
#>
		public <#= name #> With<#= pair.Key #>(<#= pair.Value #> new<#= pair.Key #>)
		{
			return new <#= name #> (<# foreach (var p in fields) { #><#= isFirst ? "" : ", "#><# isFirst = false; #><#= p.Key == pair.Key ? "new" : "" #><#= p.Key #><# } #>);
		}
<# } #>
	}
}