sorting container

Hello

I have a ptr_container:

Code:

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ptr_vector<base> container;

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In container I store derived objects from base.

Code:

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class derived1 : public base {
};
class derived2 : public base {
public:
  int number;
};

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Derived2 class has an int member and I'd like to sort elements in container by the highest number.

I know if I had normal container I could do:

Code:

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std::sort(container.begin(), container.end(),
    tr1::bind( .. etc..

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But how can I do it in this case? What is the best way? I dont want to get things too complicated if not neccessary.

Note that classes contain enum so I know which type they are (so I can do static_cast) and only derived2 should be sorted in container. There could be also derived or derived3 objects in a container.

Any help is highly appreciated

I don't know about vectors, but for std::map, you can supply your own key comparison function.
Have a look here for an example of how to write one.

QuantumPete

The problem is I have a pointer container (not a usual container).

Quote:

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But how can I do it in this case? What is the best way? I dont want to get things too complicated if not neccessary.

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I am not sure about an in place fix, but as in QuantumPete's link to a comparator, you could write such a comparator that dereferenced and compared elements and pass that comparator to std::sort().

Quote:

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Note that classes contain enum so I know which type they are (so I can do static_cast) and only derived2 should be sorted in container. There could be also derived or derived3 objects in a container.

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If only derived2 should be sorted... then why store base pointers in the first place? I have this nagging feeling that something is really wrong with your class design.

Its not my design.. Its a 'parsing' library which I have to use and after data is parsed I have to sort the results..

However, I could copy the data in my own container and simplify the design. I dont know which option would be better.

So, the container holds a mixture of Derived1 and Derived2, and only the Derived2 elements should be sorted? Then where do the Derived1 elements go? You cannot sort unless you have a total order.

A generic dereferencing function always comes in handy...

Code:

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template <typename T>
T &deref(T *ptr)
{
    return *ptr;
}

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Once you have that, a few binds do the trick:

Code:

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std::sort(x.begin(), x.end(), bind(std::less<int>(), bind(deref<int>, _1), bind(deref<int>, _2)));

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