STL sort & virtual problem

[izis777]

I wanna sort the list with my class PrDerived. But, it doesn't occur. I think sort function creates a predicate copy and doesn't copies a virtual table. How to solve this problem ? See example:

	
	list<int> List;
	...
	struct PrBase
	{
		virtual bool operator()(const int& a, const int& b) const
		{
			...
		}
	};

	struct PrDerived : PrBase
	{
		virtual bool operator()(const int& a, const int& b) const
		{
			...
		}
	};

	PrDerived MyDerived;
	PrBase * p = &MyDerived;
	List.sort( *p );

[Ganon11]

The function list::sort takes a function pointer to compare two of its elements. What you are giving it is a struct. I don't think this was what you were going for: perhaps you meant p->operator()? You example is confusing to me, but then I've never had much luck wrapping my head around function pointers.

[izis777]

The function list::sort takes a function pointer to compare two of its elements. What you are giving it is a struct. I don't think this was what you were going for: perhaps you meant p->operator()? You example is confusing to me, but then I've never had much luck wrapping my head around function pointers.

sort() and stable_sort() sort all elements by using the binary predicate!
Functional arguments for algorithms don't have to be functions. They can be objects that behave as functions. Such an object is called a function object, or functor.