We gained an introduction to the immutable object from the preceding discussion. As you learned in the previous chapter, we can take advantage of the first-class function and pure function to create an immutable programming approach. Let's borrow the code from Chapter 2, Manipulating Functions in Functional Programming, that is first_class_1.cpp. We will have the addition(), subtraction(), multiplication(), and division() methods in our following first_class_pure_immutable.cpp code. We will then invoke the pure function on the class and assign the result to the variable. The code is written as follows:
/* first_class_pure_immutable.cpp */
#include <iostream>
using namespace std;
// MyValue class stores the value
class MyValue
{
public:
const int value;
MyValue(int v) : value(v)
{
}
};
// MyFunction class stores the methods
class MyFunction...