Add containers module with initial implementation and integrate into CMake build system.

cpp/classes/ClassA.cpp

@@ -2,6 +2,36 @@
 
 #include <iostream>
 
+ClassA::ClassA() : IComparable(), _number(0), _pDecimal(new float(0.0f)) {
+    std::cout << "ClassA()" << std::endl;
+
+    // _pDecimal = new float(0.0f);
+}
+
+ClassA::ClassA(const ClassA &other) :
+    IComparable(),
+    _number(other._number),
+    _pDecimal(new float(*other._pDecimal)) {
+
+    std::cout << "ClassA(const ClassA &other)" << std::endl;
+
+    // // for presentation only
+    // // shallow copy
+    // _number = other._number;
+    // *_pDecimal = *other._pDecimal;
+    //
+    // // deep copy
+    // _number = other._number;
+    // _pDecimal = new float(*other._pDecimal);
+}
+
+ClassA::~ClassA() {
+    std::cout << "~ClassA()" << std::endl;
+
+    delete _pDecimal;
+    _pDecimal = nullptr;
+}
+
 void ClassA::Print() {
     std::cout << "ClassA" << std::endl;
 }