回答編集履歴
2
修正
answer
CHANGED
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@@ -17,21 +17,28 @@
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#define GET_PROPERTY(X) X([this]() {return X##_; })
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// おためし
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-
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#include <iostream>
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#include <string>
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#include <chrono>
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#include <ctime>
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class person {
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private:
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// プロパティ名に'_'を付けること。
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std::string name_;
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int age_;
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+
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public:
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person(const std::string& n, int a) :
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-
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name_(n), GET_PROPERTY(name),
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-
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age_(a), GET_PROPERTY(age),
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// 引数を取らない関数ならなんでも♪
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now([]() -> std::string {
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std::time_t t = std::chrono::system_clock::to_time_t(std::chrono::system_clock::now());
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return std::ctime(&t); }) {}
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property<std::string> name;
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property<int> age;
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property<std::string> now;
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};
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int main() {
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@@ -39,6 +46,7 @@
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person adam("adam", 20);
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int age = adam.age; // do this
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cout << adam.name() << " is " // or this
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<< age << " years old
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<< age << " years old at "
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<< adam.now() << endl;
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}
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```
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1
追記
answer
CHANGED
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@@ -1,1 +1,44 @@
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1
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-
五年も前に[こんなの](https://codezine.jp/article/detail/7571)書きました。
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1
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五年も前に[こんなの](https://codezine.jp/article/detail/7571)書きました。
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2
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これをちょっといぢると:
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3
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```C++
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4
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#include <functional>
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5
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6
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template<class T>
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class property {
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private:
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std::function<T()> get;
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public:
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property(const std::function<T()>& getter) : get(getter) {}
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T operator()() const { return get(); }
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operator T() const { return get(); }
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typedef T value_type;
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};
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#define GET_PROPERTY(X) X([this]() {return X##_; })
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// おためし
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20
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+
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21
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#include <iostream>
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22
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#include <string>
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+
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class person {
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private:
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// プロパティ名に'_'を付けること。
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std::string name_;
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int age_;
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public:
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person(const std::string& n, int a) :
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name_(n), GET_PROPERTY(name),
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age_(a), GET_PROPERTY(age) {}
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property<std::string> name;
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property<int> age;
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};
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int main() {
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using namespace std;
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39
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person adam("adam", 20);
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int age = adam.age; // do this
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cout << adam.name() << " is " // or this
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<< age << " years old\n";
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}
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```
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