We have an ASP.NET Web Forms Sitecore site, where we are using HTML output caching using the OutputCache directive, VaryByCustom attribute, and an added GetVaryByCustomString() method in Global.asax.
Is it possible to get a handle to the current control from the GetVaryByCustomString() method? We're running into a problem with output caching using this method and multiple instances of a control added to the same page. If I had a handle to the control, I could cache the output separately based on its Sitecore parameters (important in this case) and still make it mesh nicely with the rest of our caching strategy.