I just went through the whole conversation on this and find it knowledgeable for me as i am beginner for cache. Now i am able to understand how to use them in with the standards and where i need to careful thanks for all. 

Thank you Michelle. Please let me know when this is fixed.

Thanks

Kishan R

So can this is be used in a parent-child class format if how will this be of use. And by using $classmethod this is there any advantage, if so can you mention some.

Thanks

Kishan R