c-resources/CPlusPlus20ForProgrammers-m.../examples/ch16/fig16_06-07 - Copy/privatefragmentdemo.ixx

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2024-04-09 06:45:18 +00:00
// Fig. 16.6: privatefragmentdemo.ixx
// Primary module interface for a module named
// privatefragmentdemo with a :private module fragment.
export module privatefragmentdemo; // introduces the module name
import <memory>; // std::unique_ptr
class Implementation; // forward class declaration
export class Integer { // interface class
public:
Integer(int value); // constructor
int getValue() const; // gets value from hidden Implementation object
std::unique_ptr<Implementation> getImplementationCopy();
private:
// pointer to object of the hidden Implementation
std::unique_ptr<Implementation> m_ptr;
};
// everything from the following module :private; declaration to the end
// of the file is hidden from importers of module privatefragmentdemo
module :private;
// hidden Implementation class used in the
// Integer interface class's member function implementations
class Implementation {
public:
explicit Implementation(int value) : m_value{value} {}
int getValue() const {return m_value;}
private:
int m_value; // data we're hiding from the client code
};
// Integer interface class's member function implementations
Integer::Integer(int value)
: m_ptr{std::make_unique<Implementation>(value)} {}
int Integer::getValue() const {return m_ptr->getValue();}
// Though we return a std::unique_ptr<Implementation>, translation units
// that import module privatefragmentdemo cannot see type Implementation.
// Attempts to use the Implementation's members fail to compile.
std::unique_ptr<Implementation> Integer::getImplementationCopy() {
return std::make_unique<Implementation>(m_ptr->getValue());
}
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