Using two objects as hash key for an unordered_map or alternatives

Question

Having defined my objects myType, I need to store relations between these objects. These relations are stored on a matrix.

The number of elements is not

Answer 1

You could use a boost::unordered_map with key std::pair in combine with boost::hash. You could declare it as:

boost::unordered_map, 
                     std::vector>, 
                     boost::hash>> dictionary;

Then you could load the characteristics of each pair in the dictionary like in the example below:

dictionary[std::make_pair(&a, &b)] = std::vector>(1, {1, 2, 3, 4, 5});

And access them as:

dictionary[std::make_pair(&a, &b)][0][0];

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