Node type with a choice of elements

This is a discussion on Node type with a choice of elements within the C++ Programming forums, part of the General Programming Boards category; So I want to create a tree with two different types of nodes, the internal nodes have pointers to further ...

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    Node type with a choice of elements

    So I want to create a tree with two different types of nodes, the internal nodes have pointers to further nodes, while the leaf nodes simply have elements. In Pascal, you can define a type with one element being a nodetype which can be defined to be either a leaf or an internal node. Then there is a case statement to decide what members are available for that node type. Is this possible in C++ classes or Structs, or something?

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    You could have a base class and make internal_node and leaf derived classes. Or you can just have a node class that can be either, and use some sort of indicator to tell which one the current node is.

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    I think I will go with the indicator, thank you

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    In fact the indicator is very simple -- if you're using a std::vector< Node * > (or std::deque, std::list, etc. ) as your list of child nodes, you just check to see if the vector is empty or not. Empty = leaf, non-empty = internal node.

    Note if you use pointers inside STL containers you *must* be careful to call delete on every pointer when you remove it from the vector. One option would be to wrap the pointers inside, say, a boost::shared_ptr and then put that into your vector.
    You ever try a pink golf ball, Wally? Why, the wind shear on a pink ball alone can take the head clean off a 90 pound midget at 300 yards.

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    (?<!re)tired Mario F.'s Avatar
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    Maybe a scoped_ptr. There's no need for sharing of ownership, I reckon
    The programmer’s wife tells him: “Run to the store and pick up a loaf of bread. If they have eggs, get a dozen.”
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    Originally Posted by brewbuck:
    Reimplementing a large system in another language to get a 25% performance boost is nonsense. It would be cheaper to just get a computer which is 25% faster.

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    Quote Originally Posted by Mario F.
    Maybe a scoped_ptr. There's no need for sharing of ownership, I reckon
    STL containers require that the elements they contain be copyable. Internally, STL implementations are permitted to make as many copies of an element as they choose.
    You ever try a pink golf ball, Wally? Why, the wind shear on a pink ball alone can take the head clean off a 90 pound midget at 300 yards.

  7. #7
    (?<!re)tired Mario F.'s Avatar
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    Ah. Gotcha!
    The programmer’s wife tells him: “Run to the store and pick up a loaf of bread. If they have eggs, get a dozen.”
    The programmer comes home with 12 loaves of bread.


    Originally Posted by brewbuck:
    Reimplementing a large system in another language to get a 25% performance boost is nonsense. It would be cheaper to just get a computer which is 25% faster.

  8. #8
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    But a ptr_vector might be a good idea. Cheaper than the shared_ptr.
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