add Template Method pattern

template-method/README.txt

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+## Template Method
+
+Template method defines the skeleton of an algorithm in an operation, deferring some
+steps to subclasses. It lets subclasses redefine certain steps of an algorithm 
+without changing the algorithm's structure. The pattern has behavioral purpose and
+applies to the classes.
+
+### When to use
+
+* to implement the invariant parts of an algorithm once and leave it up to subclasses to implement the behavior that can vary
+* when common behavior among subclasses should be factored and localizedin a common class to avoid code duplication
+* to control subclasses extensions

template-method/TemplateMethod.cpp

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+/*
+ * C++ Design Patterns: Template Method
+ * Author: Jakub Vojvoda [github.com/JakubVojvoda]
+ * 2016
+ *
+ * Source code is licensed under MIT License
+ * (for more details see LICENSE)
+ *
+ */
+
+#include <iostream>
+
+/*
+ * AbstractClass
+ * implements a template method defining the skeleton of an algorithm
+ */
+class AbstractClass {
+public:
+  void templateMethod() {
+    // ...
+    primitiveOperation1();
+    // ...
+    primitiveOperation2();
+    // ...
+  }
+
+  virtual void primitiveOperation1() = 0;
+  virtual void primitiveOperation2() = 0;
+  // ...
+};
+
+/*
+ * Concrete Class
+ * implements the primitive operations to carry out specific steps
+ * of the algorithm, there may be many Concrete classes, each implementing
+ * the full set of the required operation
+ */
+class ConcreteClass : public AbstractClass {
+public:
+  void primitiveOperation1() {
+    std::cout << "Primitive operation 1" << std::endl;
+    // ...
+  }
+
+  void primitiveOperation2() {
+    std::cout << "Primitive operation 2" << std::endl;
+    // ...
+  }
+  // ...
+};
+
+
+int main()
+{
+  AbstractClass *tm = new ConcreteClass;
+  tm->templateMethod();
+
+  return 0;
+}