#include <iostream>
 
class CLanguage
{
public:
    virtual void generate() = 0;
};
 
class CPytnon : public CLanguage
{
public:
    void generate() { std::cout << "Generate python code" << std::endl; }
};
 
class CJava : public CLanguage
{
public:
    void generate() { std::cout << "Generate java code" << std::endl; }
};
 
class CLangFactory
{
public:
    virtual CLanguage* generateCode() = 0;
};
 
class CPythonFactory : public CLangFactory
{
public:
    CLanguage* generateCode(){ return new CPytnon(); }
};
 
class CJavaFactory : public CLangFactory
{
public:
    CLanguage* generateCode() { return new CJava(); }
};
 
class CCodeGenerator
{
public:
    CCodeGenerator(CLangFactory* factory)
    {
        CLanguage *pLang = factory->generateCode();
        pLang->generate();
        delete pLang;
        delete factory;
    }
};
 
CLangFactory* createCodeFactory()
{
    int nLang = -1;
    std::cout << "Enter Language type (0: Python, 1: Java): ";
    std::cin >> nLang;
 
    switch( nLang )
    {
    case 0: return new CPythonFactory();
    case 1: return new CJavaFactory();
    default: std::cout << "Error choice language..." << std::endl; return 0;
    }
}
 
int main()
{
    CLangFactory *plf = createCodeFactory();
    if( plf )
        CCodeGenerator cg( plf );
 
    return 0;
}

class CSingleton
{
private:
    static CSingleton m_singleton;
 
private:
    CSingleton() {}
    ~CSingleton() {}
    CSingleton(const CSingleton &) {}
    CSingleton & operator=(const CSingleton &) { return *this; }
 
public:
    static CSingleton *instance() { return &m_singleton; }
};
 
CSingleton CSingleton::m_singleton;
 
int main(int , char **)
{
    CSingleton *p = CSingleton::instance();
    // ...
    return 0;
}

class CSingleton
{
private:
    static CSingleton *m_pSingleton;
    static int m_nCounter;
 
private:
    CSingleton() {}
    ~CSingleton() {}
    CSingleton(const CSingleton &) {}
    CSingleton & operator=(const CSingleton &) { return *this; }
 
public:
    static CSingleton *instance()
    {
        if( m_nCounter == 0 )
        {
            m_pSingleton = new CSingleton();
        }
        m_nCounter++;
        return m_pSingleton;
    }
    static CSingleton *freeInstance()
    {
        if( m_nCounter > 0 )
        {
            m_nCounter--;
            if( m_nCounter == 0 )
            {
                delete m_pSingleton;
                m_pSingleton = 0;
            }
        }
    }
};
 
CSingleton *CSingleton::m_pSingleton = 0;
int CSingleton::m_nCounter = 0;
 
int main(int , char **)
{
    CSingleton *p = CSingleton::instance();
 
    return 0;
}

class CClass
{
public:
    virtual ~CClass(){  }
};
 
template <class T>
class CTypedSingleton;
 
template<class T>
class CTypedWrapper : public T, private CTypedSingleton<T>
{
public:
    void operator delete(void *p)
    {
        CTypedSingleton<T>::free();
    }
};
 
template <class T>
class CTypedSingleton
{
    static T* m_self;
    static int m_refcount;
 
protected:
    CTypedSingleton(){}
    CTypedSingleton(const CTypedSingleton&){}
    virtual ~CTypedSingleton(){ m_self = 0; }
    CTypedSingleton &operator=(const CTypedSingleton&){}
 
public:
  static T *init()
  {
      if(!m_self)
          m_self = new CTypedWrapper<T>;
      m_refcount++;
      return m_self;
  }
 
  static void free()
  {
      if( m_refcount > 0)
      {
          --m_refcount;
          if( m_refcount == 0)
          {
              delete m_self;
              m_self = 0;
          }
      }
  }
};
 
template <class T>
T *CTypedSingleton<T>::m_self = 0;
 
template <class T>
int CTypedSingleton<T>::m_refcount = 0;
 
int main(int , char **)
{
    CClass *p = CTypedSingleton<CClass>::init();
    delete p;
 
    return 0;
}

#include <cstdlib>
#include <boost/thread/once.hpp>
 
template <class T>
class Singleton
{
public:
    static T& Instance();
 
private:
    Singleton() {};
    Singleton(const Singleton&);
    Singleton& operator=(const Singleton&);
    virtual ~Singleton() {};
 
    static void Init() { boost::call_once(m_init, &Singleton<T>::InitImpl); }
    static void InitImpl() { m_me = new T; atexit(&Singleton<T>::FreeInstance); }
    static void FreeInstance() { boost::call_once(m_done, &Singleton<T>::FreeImpl); };
    static void FreeImpl() { delete m_me; m_me = NULL; }
    friend int atexit(void (__cdecl *func)(void));
 
private:
    static T* volatile m_me;
    static boost::once_flag m_init, m_done;
};
 
template <class T>
T* Singleton<T>::m_me = NULL;
 
template <class T>
boost::once_flag Singleton<T>::m_init = BOOST_ONCE_INIT;
 
template <class T>
boost::once_flag Singleton<T>::m_done = BOOST_ONCE_INIT;
 
template <class T>
T& Singleton<T>::Instance()
{
      Init();
      return (*m_me);
}

#include <iostream>
 
// Прототип
class CPrototype
{
public:
    virtual CPrototype* clone() const = 0;
};
 
// Прототип сайта
class CSitePrototype : public CPrototype
{
private:
    int m_nPages;
 
public:
    CSitePrototype(int nPages) : m_nPages( nPages ){}
    CSitePrototype(const CSitePrototype &r) : m_nPages( r.m_nPages ){}
    virtual CSitePrototype* clone() const { return new CSitePrototype( *this ); }
 
    void setPages(int nPages) { m_nPages = nPages; }
    int getPages() const { return m_nPages; }
    void printPages() const { std::cout << "Pages: " << m_nPages << std::endl; }
};
 
// Клиентская сторона
void clientSide()
{
    CPrototype *pPrototype = new CSitePrototype( 256 );
    for (int n = 0; n < 10; n++)
    {
        CSitePrototype *pSite = static_cast<CSitePrototype*>( pPrototype->clone() );
        pSite->setPages( pSite->getPages() * n );
        pSite->printPages();
        delete pSite;
    }
    delete pPrototype;
    pPrototype = 0;
}
 
int main()
{
    clientSide();
    return 0;
}

#include <string>
#include <iostream>
 
class CCode
{
private:
    std::string m_szCode;
 
public:
    void build(const std::string &rCode) { m_szCode = rCode; }
    void print() const { std::cout << "Code: " << m_szCode << std::endl; }
};
 
// Abstract Builder
class CCodeBuilder
{
protected:
    CCode m_code;
 
public:
    const CCode& code() { return m_code; }
 
    virtual void buildCode() = 0;
};
 
class CPythonBuilder : public CCodeBuilder {
public:
    void buildCode() { m_code.build("cpp code"); }
};
 
class CJavaBuilder : public CCodeBuilder
{
public:
    void buildCode() { m_code.build("delphi code"); }
};
 
class CDeveloper
{
private:
    CCodeBuilder *m_pCodeBuilder;
 
public:
    CDeveloper(): m_pCodeBuilder(0){}
    virtual ~CDeveloper() { freeCodeBuilder(); }
 
    void freeCodeBuilder()
    {
        if( m_pCodeBuilder )
        {
            delete m_pCodeBuilder;
            m_pCodeBuilder = 0;
        }
    }
 
    void setCodeBuilder(CCodeBuilder* pCodeBuilder)
    {
        freeCodeBuilder();
        m_pCodeBuilder = pCodeBuilder;
    }
    const CCode& getCode() { return m_pCodeBuilder->code(); }
    void constructCode() { m_pCodeBuilder->buildCode(); }
};
 
int main()
{
    CDeveloper dev;
 
    dev.setCodeBuilder(new CPythonBuilder);
    dev.constructCode();
    CCode python = dev.getCode();
    python.print();
 
    dev.setCodeBuilder(new CJavaBuilder);
    dev.constructCode();
    CCode java = dev.getCode();
    java.print();
}