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copied!<p><strong>To handle validation do one of these:</strong></p> <ul> <li>Validate with a method inside the user control</li> <li><p>Have your user control have a <a href="http://msdn.microsoft.com/en-us/library/ms173171(VS.80).aspx" rel="nofollow noreferrer"><code>delegate</code></a> property (e.g. <code>ValidationHandler</code>) that can handle the validation (this would allow you to have a class with a bunch of validators that you could assign to your controls)</p> <p><code>public delegate void Validator(...)</code></p> <p><code>public Validator ValidationHandler { get; set; }</code></p></li> <li><p>Have your user control generate a validation request <a href="http://msdn.microsoft.com/en-us/library/awbftdfh.aspx" rel="nofollow noreferrer"><code>event</code></a> (e.g. <code>ValidationRequested</code>)</p> <p><code>public event EventHandler<ValidationEventArgs> ValidationRequested</code></p></li> </ul> <p><strong>To notify the system that an error has occurred do one of these:</strong></p> <ul> <li><p>Use an <a href="http://msdn.microsoft.com/en-us/library/awbftdfh.aspx" rel="nofollow noreferrer"><code>event</code></a> that interested parties can subscribe to (e.g. <code>ValidationFailed</code>)</p></li> <li><p>If the object that performs the validation (via the <code>delegate</code> or <code>event</code>) is also the one that you want to generate the error message from, it can raise the error message itself.</p></li> </ul> <p><strong>EDIT:</strong></p> <p>Since you've said you would validate inside your control, the code for a ValidationFailed event might look like:</p> <pre><code>// In your user control public class ValidationFailedEventArgs : EventArgs { public ValidationFailedEventArgs(string message) { this.Message = message; } public string Message { get; set; } } private EventHandler<ValidationFailedEventArgs> _validationFailed; public event EventHandler<ValidationFailedEventArgs> ValidationFailed { add { _validationFailed += value; } remove { _validationFailed -= value; } } protected void OnValidationFailed(ValidationFailedEventArgs e) { if(_validationFailed != null) _validationFailed(this, e); } private void YourValidator() { if(!valid) { ValidationFailedEventArgs args = new ValidationFailedEventArgs("Your Message"); OnValidationFailed(args); } } // In your main form: userControl.ValidationFailed += new EventHandler<ValidationFailedEventArgs>(userControl_ValidationFailed); // ... private void userControl_ValidationFailed(object sender, ValidationFailedEventArgs e) { statusBar.Text = e.Message; } </code></pre>

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