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copied!<p>You can use the Singleton pattern to assure that only one instance is ever created. </p> <p>However, <a href="https://stackoverflow.com/questions/11831/singletons-good-design-or-a-crutch">the jury is still out</a> (at least in my mind) on whether this is a good decision. There's plenty of reading on SO and other places about this.</p> <p>I would approach this from a different angle. I'd make all of my forms take in a Person instance in the constructor. That way, each form is only ever worried about it's instance of Person. </p> <p>You could do this by creating a new class that inherits from Form and has a field/property/constructor for your Person. Then, any form that uses Person can inherit from your new class.</p> <p>You would, of course, have to manage the creation of your Person object. You could even do this with a singleton. However, the benefit is that each form doesn't have to know how to create a Person or who created the Person. That way, if you choose to <a href="https://stackoverflow.com/questions/474613/how-should-i-refactor-my-code-to-remove-unnecessary-singletons">move away from the Singleton pattern</a>, you wouldn't have to go change all of your references to your singleton instance.</p> <p><strong>EDIT:</strong></p> <p>Here's some code to demonstrate this. It took me a while to get the designer to play nice. I had to add an empty private constructor in PersonForm to get the designer to not throw an error.</p> <p>Program.cs</p> <pre><code>static class Program { /// <summary> /// The main entry point for the application. /// </summary> [STAThread] static void Main() { Application.EnableVisualStyles(); Application.SetCompatibleTextRenderingDefault(false); Application.Run(new MyDerivedForm(new Person { Name = "Hello World!" })); } } </code></pre> <p>Person.cs</p> <pre><code>public class Person { public virtual string Name { get; set; } } </code></pre> <p>PersonForm.cs</p> <pre><code>using System; using System.Windows.Forms; public class PersonForm : Form { private readonly Person myPerson; protected virtual Person MyPerson { get { return this.myPerson; } } private PersonForm() { } public PersonForm(Person person) { this.myPerson = person; } } </code></pre> <p>MyDerivedForm.cs (add a label named label1)</p> <pre><code>public partial class MyDerivedForm : SingletonMadness.PersonForm { public MyDerivedForm(Person person) : base(person) { InitializeComponent(); } private void MyDerivedForm_Load(object sender, EventArgs e) { label1.Text = this.MyPerson.Name; } } </code></pre>

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