.net - Storing subcollections (filtered versions of the main collection) inside the collection as cache? -

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is practice store sub-collections of item x inside parent collection of item x caching 'filter-queries' performed on parent collection? (they won't used (as in color , type).) or ok loop on collection , return correct entities in temporary collection?

class itemcollection : inherits collection(of item)     private _types new list(of itemcollection) //cache      function filterbytype(type) itemcollection         if not _types.keyexists(type)             _types.add(type, new itemcollection())             each in me                 if i.type = type _types(type).add(i)             next         end if         return _types(type)     end function      //same filterbycolor(color) end class  class item     public color = "blue"     public [type] = "one" end class

i recommend keeping simple start , add caching if testing shows regenerating filtered lists performance problem. besides that, filtering code can simplified using filtering methods built list or using linq extensions.

filtered = me.where(i => i.type = type)

(i off on exact syntax, i've never done linq in vb.net, i'm c# guy.)


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