c++ - Building an index: Copies or pointers? -

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I have a data structure that stores ... well, data. Now, I need to reach different pieces of data in a slightly different way, so I'm essentially building an in-memory index. But I'm thinking: should there be index pointers or copies?

To expand, say that I have 

  class widget {// how to access the list of gear .. private: std :: list & lt; Gears & gt; M_gears; };

Now, I have two widgets s, and between them there is a mapping between their gear s presently , This 

  boost :: unmodified_map> Gear, gear & gt;

But gear is quite heavy square, and I think making such copies is bad design. I can store an indicator, but then mapping is valid for the lifetime of this widget s, and you can call - & gt; s ... (and if the std :: list turns into std :: vector , it becomes more complex Is ...)

In relation to copies, it is actually a bit bad: two boost :: unordered_map s, one for each direction, therefore, every gear For , I'm making it up to 2 copies.

Alternatively, I can put the index inside the widget class, but I think it violates the widget class responsibilities .

You can try Boost Pointer Container Library:

I think That this is exactly the problem you are facing.


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