Dependency question

Is it possible to make cache entries dependant on other cache entries?

i.e.
    Doc1 denpendant on [Doc2, Doc3, Doc....]
    Remove Doc2 and Doc1 is also removed because its dependency is missing

How about making a cache entry dependant on a filesystem object?

i.e.
    SomeFile.txt is read and cached. The file changes so the cache entry 
is invalidated.
      
Thanks

-Cam



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