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81 lines
1.4 KiB
C++
81 lines
1.4 KiB
C++
#include <iostream>
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#include <stdexcept>
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#include <typeinfo>
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class Nail {
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public:
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explicit Nail(float length)
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: length(length) {}
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float getLength() {
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return length;
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}
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private:
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float length;
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};
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class Tool {
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public:
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virtual void use() {
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std::cout << "Just using some tool." << std::endl;
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}
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};
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class Hammer : public Tool {
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public:
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virtual void use() {
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std::cout << "Hammer time!" << std::endl;
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}
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void use(Nail nail) {
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std::cout << "The nail is " << nail.getLength() << " cm long"
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<< std::endl;
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}
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};
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class SledgeHammer : public Hammer {
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public:
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void use(Nail nail __attribute__((unused))) {
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throw std::runtime_error("Can't use a sledge hammer on nails!");
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}
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};
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void useSomeTool(Tool &tool) {
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// RTTI gives up the type of the derived class.
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std::cout << "Look, it's a " << typeid(tool).name() << "!" << std::endl;
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// XXX What about subclasses of Hammer?
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if (typeid(tool) == typeid(Hammer)) {
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std::cout << "Stop! ";
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}
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tool.use();
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// Or dynamic_cast it and use it on a nail
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// XXX How to use a reference here?
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Hammer* h = dynamic_cast<Hammer*>(&tool);
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if (h) {
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Nail nail(10);
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h->use(nail);
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}
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}
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int main() {
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Tool tool;
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Hammer hammer;
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SledgeHammer sledgehammer;
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useSomeTool(tool);
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useSomeTool(hammer);
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useSomeTool(sledgehammer);
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}
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// XXX http://en.cppreference.com/w/cpp/language/typeid
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// XXX https://en.wikipedia.org/wiki/Dynamic_cast
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