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  1. #include <memory>
  2.  
  3. namespace restricted
  4. {
  5.     struct A
  6.     {
  7.         virtual ~A() {}
  8.         virtual int value_a() const { return a ; }
  9.  
  10.         protected:
  11.             int a = 0 ;
  12.             virtual void value_a( int i ) { a = i ; }
  13.     };
  14.  
  15.     struct B : A
  16.     {
  17.         virtual int value_b() const { return b ; }
  18.  
  19.         protected:
  20.             int b = 0 ;
  21.             virtual void value_b( int i ) { b = i ; }
  22.     };
  23. }
  24.  
  25. namespace exposed
  26. {
  27.     struct A : restricted::A
  28.     {
  29.         using restricted::A::value_a ;
  30.     } ;
  31.  
  32.     struct B : restricted::B
  33.     {
  34.         using restricted::B::value_a ;
  35.         using restricted::B::value_b ;
  36.     } ;
  37. }
  38.  
  39. int main()
  40. {
  41.     auto exposed_a = std::make_shared<exposed::A>() ;
  42.     int v = exposed_a->value_a() ;
  43.     exposed_a->value_a(v) ; // fine, exposed
  44.  
  45.     auto exposed_b = std::make_shared<exposed::B>() ;
  46.     v = exposed_b->value_a() ;
  47.     exposed_b->value_a(v) ; // fine, exposed
  48.     v = exposed_b->value_b() ;
  49.     exposed_b->value_b(v) ; // fine, exposed
  50.  
  51.     std::shared_ptr<restricted::A> restricted_a(exposed_a) ; // fine, exposed::A => restricted::A
  52.  
  53.     v = restricted_a->value_a() ; // fine
  54.     // restricted_a->value_a(v) ; // *** error **** restricted::A::value_a(int) is protected
  55.  
  56.     restricted_a = exposed_b ; // also fine, exposed::B => restricted::A
  57.  
  58.     std::shared_ptr<restricted::B> restricted_b(exposed_b) ; // fine, exposed::B => restricted::B
  59.  
  60.     v = restricted_b->value_a() ; // fine
  61.     // restricted_b->value_a(v) ; // *** error **** restricted::B::value_a(int) is protected
  62.     v = restricted_b->value_b() ; // fine
  63.     // restricted_b->value_b(v) ; // *** error **** restricted::B::value_b(int) is protected
  64. }
  65.  
Success #stdin #stdout 0s 3428KB
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https://ideone.com/k0cA1O
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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