new file mode 100644

@@ -0,0 +1,59 @@

+#include "crany.hpp"

+

+#include <cmath>

+#include <iostream>

+#include <vector>

+

+

+auto constexpr pi = std::acos(-1.0F);

+

+

+struct Circle

+{

+    float radius;

+    void  scale(float scale)       { radius *= scale;         }

+    float area()             const { return pi*radius*radius; }

+    float circumference()    const { return 2.0F*pi*radius;   }

+};

+

+struct Rectangle

+{

+    float side1;

+    float side2;

+    void  scale(float scale)       { side1 *= scale; side2 *= scale; }

+    float area()             const { return side1*side2;             }

+};

+

+

+template<typename Self>

+struct ShapeConcept : Self

+{

+    using Self::self;

+    virtual void  scale(float value)       { return self().scale(value); }

+    virtual float area()             const { return self().area();       }

+};

+

+using Shape = Crany<ShapeConcept>;

+using Shapes = std::vector<Shape>;

+

+

+int main()

+{

+    static_assert(std::is_standard_layout   <Circle>{}, "Circle not is standard layout");

+    static_assert(std::is_trivially_copyable<Circle>{}, "Circle not is trivially copyable");

+

+    auto shapes = Shapes{

+        Circle{1.0F},

+        Rectangle{2.0F, 3.0F},

+    };

+    shapes.push_back(shapes.front());

+    shapes.back().scale(2.0F);

+

+    std::cout << std::boolalpha;

+    for (auto const & shape : shapes)

+        std::cout

+            << shape.area()

+            << " "

+            << bool(crany_cast<Circle>(&shape))

+            << "\n";

+}