1 files changed, 74 insertions, 0 deletions
diff --git a/abstract.cpp b/abstract.cpp
new file mode 100644
index 0000000..99edd52
--- /dev/null
+++ b/abstract.cpp
@@ -0,0 +1,74 @@
+#include <iostream>
+#include <string>
+
+/* below tweak needs to know wbout this class */
+template <class T>
+class Polygon;
+
+/* convine the compiler that overloaded operators are templates themselves before
+ * we reach the declaration of the class */
+template <class T>
+std::ostream& operator<<(std::ostream &, const Polygon<T> &);
+
+template <class T>
+class Polygon
+{
+    public:
+        /* notice the <> after function name, we're letting g++ know this is a template */
+        friend std::ostream& operator<<<>(std::ostream &, const Polygon<T> &);
+
+        /* pure virtual, subclass must DEFINE it. otherwise that subclass itself
+         * will remain abstract and won't be able to be instantiated */
+        virtual T area(void) = 0;
+
+        T getWidth(void) {
+            this->width;
+        }
+
+        T getHeight(void) {
+            this->height;
+        }
+
+    protected:
+        T width, height;
+        std::string type; /* name of polygon */
+};
+
+template <class T>
+class Triangle : public Polygon<T>
+{
+    public:
+        Triangle() {
+            this->width = 0;
+            this->height = 0;
+            this->type = std::string("triangle");
+        }
+
+        Triangle(int b, int h) {
+            this->width = b;
+            this->height = h; /* this keyword has to be used? */
+            this->type = std::string("triangle");
+        }
+
+        virtual T area(void) {
+            return (this->width * this->height) / 2;
+    }
+};
+
+template <class T>
+std::ostream& operator<<(std::ostream& stream, const Polygon<T>& p)
+{
+    stream << p.type << " dimensions, width: " << p.width << ", height: " << p.height
+           << ", area: "<< const_cast<Polygon<T> *>(&p)->area(); /* lol at the cast! */
+
+    return stream;
+}
+
+int main(int argc, char *argv[])
+{
+    Triangle<int> tri(6, 4);
+    std::cout << tri << std::endl;
+
+    return 0;
+}
+