Is an object creating using an "inline" new statement automatically disposed?

Question

The following snippet is taken from an example of ComboBox::DrawItem implementation on this MSDN page:

e.Graphics.FillRectangle(new SolidBrush(animalColor), rectangle);

I question this part: new SolidBrush(animalColor)

Since this is neither deliberately given a Dispose nor is it wrapped in a using, I assume this is also an example of poor form, since the SolidBrush object will be created and never disposed.

I have always labored under the assumption that I must use one of the aforementioned disposal mechanisms directly, or risk a memory leak.

Am I correct, or is there some deeper implicit disposal going on of which I am unaware? Perhaps because it was never assigned to a variable?

Answer 1

It should be inside a using statement or it should explicitly call Dispose, but,

SolidBrush class inherits Brush class which has a destructor/finalize defined as:

Source from here:

   /**
     * Object cleanup
     */
    /// <include file='doc\Brush.uex' path='docs/doc[@for="Brush.Finalize"]/*' />
    /// <devdoc>
    ///    <para>
    ///       Releases memory allocated for this <see cref='System.Drawing.Brush'/>.
    ///    </para>
    /// </devdoc>
    ~Brush() 
    {
        Dispose(false);
    }

Once your object of class SolidBrush goes out of scope, Ultimately its destructor will be called. At that point Dispose will be called releasing any unmangaged resources.

See: Destructors (C# Programming Guide)

The destructor implicitly calls Finalize on the base class of the object.

The only issue with relying on destructor/finalizer is, that, you can't predict when the object will finally be disposed.

Answer 2

I should say that's a poor example from msdn. You ought to Dispose it; no object will be disposed automatically.

It is not necessarily a leak, Brush implements a Finalizer which will Dispose it when garbage collected but you shouldn't rely on this.