I recently faced to some limitations with RenderSupport. I wanted to decorate it but I realized that this filter is not a service. What a shame, one of the most important Tapestry 5 service is not customisable…

Really? No. There is a possibility to decorate RenderSupport, and in fact any of MarkupRendererFilter and Environment objects.

How to achieve that?

• Create a new RenderSupport implementation that will wrap the initial object. It’s just like we normally do when creating a decorator.
• Create a MarkupRendererFilter that will pop RenderSupport from Environment
• Create a the interceptor from the poped RenderSupport and push it into the Environment.
• Contribute to MarkupRenderer’s ordered configuration and add your filter just after RenderSupport.

    public void contributeMarkupRenderer(OrderedConfiguration<MarkupRendererFilter> configuration)    {
        MarkupRendererFilter renderSupportInterceptor = new MarkupRendererFilter()
        {
            public void renderMarkup(MarkupWriter writer, MarkupRenderer renderer)
            {
                RenderSupport delegate = (RenderSupport) environment.pop(RenderSupport.class);
                RenderSupport interceptor = new RenderSupportInterceptor(delegate);

                environment.push(RenderSupport.class, interceptor);
                renderer.renderMarkup(writer);
            }
        };
        configuration.add("RenderSupportDecorator", renderSupportInterceptor, "after:RenderSupport", "before:ClientBehaviorSupport",
                "before:InjectDefaultStyleheet", "before:Heartbeat");
    }