Re: Pimpl idiom without dynamic memory allocation

// In the header of your class called Line

#include <string>

class Line
{
public:
   Line(const std::string& name);
   const std::string& GetName() const;
   void SetName(const std::string& s);

private:
   // Private implementation idiom:
   // all member variables are hidden in this class
   class LineImpl;
   const LineImpl& m_pimpl; // normally a non-const pointer
};

// and in your implementation file:

#include "Line.h"

// Here we define the class with the member variables
class Line::LineImpl
{
public:
   LineImpl(const std::string& s) : m_s(s) {}
   // all methods need to be const here
   const std::string& GetName() const { return m_s; }
   void SetName(const std::string& s) const { m_s = s; }
private:
   mutable std::string m_s; // the trick! all members are mutable
};

// create the pimpl instance without using new
Line::Line(const std::string& s) : m_pimpl(LineImpl(s)) {}