Dependency Injection / Decorator pattern (SOLID)

// Interface Segregation Principle

// No client should be forced to depend on methods it does not use
#include "stdafx.h"
#include <vector>

struct Document;

//struct IMachine
//{
//  virtual void print(std::vector<Document*> docs) = 0;
//  virtual void scan(std::vector<Document*> docs) = 0;
//  virtual void fax(std::vector<Document*> docs) = 0;
//};
//
//struct MFP : IMachine
//{
//  void print(std::vector<Document*> docs) override;
//  void scan(std::vector<Document*> docs) override;
//  void fax(std::vector<Document*> docs) override;
//};

struct IPrinter
{
  virtual void print(std::vector<Document*> docs) = 0;
};

struct IScanner
{
  virtual void scan(std::vector<Document*> docs) = 0;
};

struct IFax
{
    virtual void fax(std::vector<Document*> docs) = 0;
};

struct Printer : IPrinter
{
  void print(std::vector<Document*> docs) override;
};

struct Scanner : IScanner
{
  void scan(std::vector<Document*> docs) override;
};

struct Fax:IFax
{
    void fax(std::vector<Document*> docs) override;
};

//Dependecy injection
struct IMachine : IPrinter, IScanner {};

//Decorator pattern
struct Machine : IMachine
{
  IPrinter& printer;
  IScanner& scanner;

  Machine(IPrinter& printer, IScanner& scanner)
    : printer{printer},
      scanner{scanner}
  {
  }

  void print(std::vector<Document*> docs) override {
    printer.print(docs);
  }
  void scan(std::vector<Document*> docs) override {
    scanner.scan(docs);
  }
};