ASP.NET Custom Control - What is the best way to include embedded CSS reference only once?

Question

The problem: I am embedding a CSS file into a custom control library with several controls. I want to share the same CSS file for all of the controls regardless of how many

Answer 1

Why not just create a private boolean variable in the control which you set to true when the CSS is initially created. You can then check this when the method is called to see if the css has already been set. Example below (my VB is rusty so might be slighty wrong)

Private _hasCss As Boolean = False

Public Sub IncludeStyles(ByVal Page As System.Web.UI.Page)
    'Don't include the reference if it already exists...
    If Not _hasCss Then
        Dim cssUrl As String = Page.ClientScript.GetWebResourceUrl(GetType(Common), StylePath)

        Dim css As New System.Web.UI.HtmlControls.HtmlGenericControl("link")
        With css
            .Attributes.Add("rel", "stylesheet")
            .Attributes.Add("type", "text/css")
            .Attributes.Add("href", cssUrl)
            .ID = "MyID"
        End With

        Page.Header.Controls.Add(css)
        _hasCss = True

    End If
End Sub