Template -- Diamond ring Problem

Collapse
This topic is closed.
X
X
Collapse
 
  • Page of 1
  • Time
  • Show
Clear All
new posts
Previous template Next
  • Pallav singh
    #1

    Template -- Diamond ring Problem

    I am Facing Problem while creating object of Diamond Ring problem
    solving using Template
    Kindly let me known where i am committing ERROR

    Thanks
    Pallav

    #include<iostre am.h>
    #include<string .h>

    template<typena me T>
    class A
    {
    private :
    T a;

    public :
    A(T a1):a(a1){}
    A(const A<T>& a){}

    ~A(){}

    void Get_Value()cons t
    {cout<<"Value of a :: "<< a <<endl<<"\n"; }

    };


    template<typena me T ,typename U>
    class B :virtual public A<T>
    {
    private :
    U b;
    U c;

    public :

    B(T a1,U b1):A<T>(a1),b( b1),c(b1){}
    B(const B<T,U>& b){}

    ~B(){}

    void Show_Value_B()c onst
    { cout<<"Value of B___ b is :: "<<b <<endl<<"\n";
    cout<<"Value of B___ c is :: "<<c <<endl<<"\n";
    }
    };

    template<typena me T ,typename V>
    class C :virtual public A<T>
    {
    private :
    V b;
    V c;
    public :

    C(T a1,V b1):A<T>(a1),b( b1),c(b1){}
    C(const C<T,V>& c){}

    ~C(){}

    void Show_Value_C()c onst
    { cout<<"Value of C___ b is :: "<<b <<endl<<"\n";
    cout<<"Value of C___ c is :: "<<c <<endl<<"\n";
    }
    };


    template<typena me T,typename U ,typename V>
    class D :virtual public B<T,U>, virtual public C<T,V>
    {
    public :
    D(T a,U b,V c):B<T,U>(a,b), C<T,V>(a,c){}
    D(const D<T,U,V&d){}
    ~D(){};
    };


    int main(int argc , char *argv[])
    {
    D<int,char,floa tb(12,'V',17.8) ;
    b.Get_Value();
    b.Show_Value_C( );
    b.Show_Value_B( );

    return 0;
    }
    Tags: None
    • Salt_Peter
      #2
      Re: Template -- Diamond ring Problem

      On Dec 27, 2:55 am, Pallav singh <singh.pal...@g mail.comwrote:
      I am Facing Problem while creating object of Diamond Ring problem
      solving using Template
      Kindly let me known where i am committing ERROR
      read:
      [25.9] Where in a hierarchy should I use virtual inheritance?
      Inheritance -- multiple and virtual inheritance, C++ FAQ
      http://www.parashift.com/c++-faq-lite/multiple-inheritance.html#faq-25.9

      >
      Thanks
      Pallav
      >
      #include<iostre am.h>
      #include<string .h>
      #include <iostream>
      #include <string>
      >
      template<typena me T>
      class A
      {
      private :
      T a;
      >
      public :
      A(T a1):a(a1){}
      A(const T a1) : a(a1) { }
      or
      A(const T& t) : a(t) { }

      If T is any primitive type, like integer, the constructor will work
      well with the first case.
      If T were a complex user-type, a const reference is much, much better.

      I use the second case exclusively unless its specifically prohibited.
      In your case, you might prefer an explicit ctor.
      A(const A<T>& a){}
      >
      ~A(){}
      >
      void Get_Value()cons t
      {cout<<"Value of a :: "<< a <<endl<<"\n"; }
      void Get_Value() const
      {
      std::cout << "Value of a :: " << a;
      std::cout << std::endl << std::endl;
      }

      although that function should be a friend operator<< overload
      What if T is not a primitive type?
      >
      };
      >
      template<typena me T ,typename U>
      class B :virtual public A<T>
      template < typename T ,typename U >
      class B : public virtual A< T >
      {
      private :
      U b;
      U c;
      >
      public :
      >
      B(T a1,U b1):A<T>(a1),b( b1),c(b1){}
      B(const B<T,U>& b){}
      >
      ~B(){}
      >
      void Show_Value_B()c onst
      { cout<<"Value of B___ b is :: "<<b <<endl<<"\n";
      cout<<"Value of B___ c is :: "<<c <<endl<<"\n";
      }
      };
      >
      template<typena me T ,typename V>
      class C :virtual public A<T>
      {
      private :
      V b;
      V c;
      public :
      >
      C(T a1,V b1):A<T>(a1),b( b1),c(b1){}
      C(const C<T,V>& c){}
      >
      ~C(){}
      >
      void Show_Value_C()c onst
      { cout<<"Value of C___ b is :: "<<b <<endl<<"\n";
      cout<<"Value of C___ c is :: "<<c <<endl<<"\n";
      }
      };
      B and C should really be one class
      >
      template<typena me T,typename U ,typename V>
      class D :virtual public B<T,U>, virtual public C<T,V>
      Don't bother trying to construct a mesh, deal with a diamond first.
      B and C are not virtual.
      If they were, you wouldn't be able to generate an instance of D.

      template < typename T, typename U, typename V>
      class D : public B< T, U >, public C< T, V >
      {
      public :
      D(T a,U b,V c):B<T,U>(a,b), C<T,V>(a,c){}
      D(const T& a, const U& b, const V& c)
      : A< T >(a), // somebody has to do it
      B< T, U >(a,b),
      C< T, V >(a,c)
      {}


      D(const D<T,U,V&d){}
      ~D(){};
      };
      >
      int main(int argc , char *argv[])
      {
      D<int,char,floa tb(12,'V',17.8) ;
      b.Get_Value();
      b.Show_Value_C( );
      b.Show_Value_B( );
      if you had op<< available for each class, you could display the entire
      mess with one line.
      std::cout << b << std::endl;
      >
      return 0;
      >
      }

        Comment

        • Pavel Shved
          #3
          Re: Template -- Diamond ring Problem

          On 27 ÄÅË, 12:25, Salt_Peter <pj_h...@yahoo. comwrote:
          On Dec 27, 2:55 am, Pallav singh <singh.pal...@g mail.comwrote:
          >
          void šGet_Value() const
          {
          š std::cout << "Value of a :: š" << a;
          š std::cout << std::endl << std::endl;
          >
          }
          >
          although that function should be a friend operator<< overload
          What if T is not a primitive type?
          Exactly what we're trying to achieve: print T in the way we don't know
          yet but require to exist. That's called `generic programming', ever
          heard of that?
          Don't bother trying to construct a mesh, deal with a diamond first.
          B and C are not virtual.
          If they were, you wouldn't be able to generate an instance of D.
          What are you talking about? oO If that's the reason why we can't
          generate instance of D we couldn't generate instances of B and C as
          well then! Let alone that the code above (with a little fixup to D's
          constructor) compiles and runs correctly.

          š š šD(const T& a, const U& b, const V& c)
          š š š š š š š š š š š š š š : A< T >(a), // somebody has to do it
          imho this doesn't catch the problem. `Somebody' has already `done' it,
          even two times (B and C constructors)!

            Comment

            • Salt_Peter
              #4
              Re: Template -- Diamond ring Problem

              On Dec 27, 4:46 am, Pavel Shved <Pavel.Sh...@gm ail.comwrote:
              On 27 ÄÅË, 12:25, Salt_Peter <pj_h...@yahoo. comwrote:
              >
              On Dec 27, 2:55 am, Pallav singh <singh.pal...@g mail.comwrote:
              >
              void šGet_Value() const
              {
              š std::cout << "Value of a :: š" << a;
              š std::cout << std::endl << std::endl;
              >
              }
              >
              although that function should be a friend operator<< overload
              What if T is not a primitive type?
              >
              Exactly what we're trying to achieve: print T in the way we don't know
              yet but require to exist. That's called `generic programming', ever
              heard of that?
              Uhuh, generic programming supposes that T be printable. What if T is
              not a primitive type or a std::string, etc.
              So i'll throw your statement right back at you: have *YOU* ever heard
              of generic programming?
              (think: T must provide an op<<)
              >
              Don't bother trying to construct a mesh, deal with a diamond first.
              B and C are not virtual.
              If they were, you wouldn't be able to generate an instance of D.
              >
              What are you talking about? oO If that's the reason why we can't
              generate instance of D we couldn't generate instances of B and C as
              well then! Let alone that the code above (with a little fixup to D's
              constructor) compiles and runs correctly.
              Thats my mistake
              >
              š š šD(const T& a, const U& b, const V& c)
              š š š š š š š š š š š š š š : A< T >(a), // somebody has to do it
              >
              imho this doesn't catch the problem. `Somebody' has already `done' it,
              even two times (B and C constructors)!
              not if you remove those constructors in B and C, kindof obvious.
              Or was i suppose to do what you didn't do - remove A's ctors in B and
              C?
              Please

                Comment

                • Pavel Shved
                  #5
                  Re: Template -- Diamond ring Problem

                  On 27 дек, 21:58, Salt_Peter <pj_h...@yahoo. comwrote:
                  On Dec 27, 4:46 am, Pavel Shved <Pavel.Sh...@gm ail.comwrote:
                  >
                  >
                  >
                  On 27 ÄÅË, 12:25, Salt_Peter <pj_h...@yahoo. comwrote:
                  >
                  On Dec 27, 2:55 am, Pallav singh <singh.pal...@g mail.comwrote:
                  >
                  void Å¡Get_Value() const
                  {
                  Å¡ std::cout << "Value of a :: Å¡" << a;
                  Å¡ std::cout << std::endl << std::endl;
                  >
                  }
                  >
                  although that function should be a friend operator<< overload
                  What if T is not a primitive type?
                  >
                  Exactly what we're trying to achieve: print T in the way we don't know
                  yet but require to exist.  That's called `generic programming', ever
                  heard of that?
                  >
                  Uhuh, generic programming supposes that T be printable. What if T is
                  not a primitive type or a std::string, etc.
                  Well, primitive and STL types are not only ones who provide printing.
                  That's wat i was talking about.
                  Now i should also mention that yielding a compile-error if T does not
                  statisfy concept requirements is what STL types do. The OP's class
                  would do the same.
                  So, back to original question, `What is if T is not a primitive type?'
                  - nothing special. OP's written the very thing he should do in that
                  particular line with printing statement.

                  Å¡ Å¡ Å¡D(const T& a, const U& b, const V& c)
                  Å¡ Å¡ Å¡ Å¡ Å¡ Å¡ Å¡ Å¡ Å¡ Å¡ Å¡ Å¡ Å¡ Å¡ : A< T >(a), // somebody has to do it
                  >
                  imho this doesn't catch the problem. `Somebody' has already `done' it,
                  even two times (B and C constructors)!
                  >
                  not if you remove those constructors in B and C, kindof obvious.
                  It seems i dont understand you. Whom did you mean by `somebody'?
                  Constructor of D? But he can not be referred to as SOMEbody because
                  he's an only CORRECT one to do it, and that's whai i've been talking
                  about.
                  Or was i suppose to do what you didn't do - remove A's ctors in B and
                  C?
                  I wasn't even going to do this as OP's problem is with D class, all
                  the other classes being absolutely correct.

                    Comment

                    Previous template Next
                    Working...