Question

In the example below, will the returned pen be destroyed(disposed) or not?

' VB'
Public Function GetPen() As System.Drawing.Pen
  Using pen As New System.Drawing.Pen(_Color, _Width)
    pen.DashStyle = _DashStyle
    Return pen
  End Using
End Function

// C#
public System.Drawing.Pen GetPen()
{
    using (System.Drawing.Pen pen = new System.Drawing.Pen(_Color, _Width)) 
    {
        pen.DashStyle = _DashStyle;
        return pen;
    }
}

[EDIT]

Just one more precision… Is the Pen object sent to the caller of GetPen by reference or ‘cloned’ like a structure? I know, this is a class, but with GDI objects I am never sure…

Will it be destroyed(disposed) the pen created in GetPen() when the external method will Dispose its pen obtained with GetPen()?

Answer 1

Yes, pen will be disposed. It’s really a bad idea though; you return a pen that’s already disposed!

What you want to do is to remove the Using statement from GetPen. The Using statement should be used by the GetPen callers:

Using pen As Pen = GetPen()
    ''// Draw with this pen
End Using

Or in C#:

using(Pen pen = GetPen())
{
    // Draw with this pen
}

[EDIT]

Yes, a reference is returned to the calling method, not a copy. That’s why if you dispose of the pen in GetPen, you can’t use that pen in the calling method 😉

Because of the fact that GetPen and the calling method point to the same Pen object, you just need to call Dispose in the calling method.