Deriving from a component and implementing IDisposable properly
- by PaulH
I have a Visual Studio 2008 C# .NET 2.0 CF project with an abstract class derived from Component. From that class, I derive several concrete classes (as in my example below).
But, when I go to exit my Form, though the Form's Dispose() member is called and components.Dispose() is called, my components are never disposed.
Can anybody suggest how I can fix this design?
public abstract class SomeDisposableComponentBase : Component
{
private System.ComponentModel.IContainer components;
protected SomeDisposableComponentBase()
{
Initializecomponent();
}
protected SomeDisposableComponentBase(IContainer container)
{
container.Add(this);
Initializecomponent();
}
private void InitializeComponent()
{
components = new System.ComponentModel.Container();
}
protected abstract void Foo();
#region IDisposable Members
bool disposed_;
/// Warning 60 CA1063 : Microsoft.Design : Ensure that 'SomeDisposableComponentBase.Dispose()' is declared as public and sealed.*
public void Dispose()
{
// never called
Dispose(true);
GC.SuppressFinalize(this);
}
protected virtual void Dispose(bool disposing)
{
// never called
if (!disposed_)
{
if (disposing && (components != null))
{
components.Dispose();
}
disposed_ = true;
}
base.Dispose(disposing);
}
#endregion
}
public SomeDisposableComponent : SomeDisposableComponentBase
{
public SomeDisposableComponent() : base()
{
}
public SomeDisposableComponent(IContainer container) : base(container)
{
}
protected override void Foo()
{
// Do something...
}
protected override void Dispose(bool disposing)
{
// never called
base.Dispose(disposing);
}
}
public partial class my_form : Form
{
private SomeDisposableComponentBase d_;
public my_form()
{
InitializeComponent();
if (null == components)
components = new System.ComponentModel.Container();
d_ = new SomeDisposableComponent(components);
}
/// exit button clicked
private void Exit_Click(object sender, EventArgs e)
{
this.Close();
}
/// from the my_form.designer.cs
protected override void Dispose(bool disposing)
{
if (disposing && (components != null))
{
// this function is executed as expected when the form is closed
components.Dispose();
}
base.Dispose(disposing);
}
}
*I note that FX-Cop is giving me a hint here. But, if I try to declare that function as sealed, I get the error:
error CS0238: 'SomeDisposableComponentBase.Dispose()' cannot be sealed because it is not an override
Declaring that function an override leads to:
'SomeDisposableComponentBase.Dispose()': cannot override inherited member 'System.ComponentModel.Component.Dispose()' because it is not marked virtual, abstract, or override
Thanks,
PaulH
