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  1. #include <iostream>
  2. #include <cassert>
  3.  
  4. class LibFoo;
  5. class LibBar;
  6.  
  7. class IfaceA;
  8. class IfaceB;
  9.  
  10. template <typename LIB> class BaseA;
  11. template <typename LIB> class BaseB;
  12.  
  13. struct IfaceA
  14. {
  15.     virtual ~IfaceA () {}
  16.     virtual operator BaseA<LibFoo> * () { return 0; }
  17.     virtual operator BaseA<LibBar> * () { return 0; }
  18.     virtual void doSomethingWith (IfaceB &) = 0;
  19. };
  20.  
  21. struct IfaceB {
  22.     virtual ~IfaceB () {}
  23.     virtual operator BaseB<LibFoo> * () { return 0; }
  24.     virtual operator BaseB<LibBar> * () { return 0; }
  25. };
  26.  
  27. template <typename LIB>
  28. struct BaseA : IfaceA {
  29.     operator BaseA * () override { return this; }
  30.  
  31.     void doSomethingWith (IfaceB &b) override {
  32.         doSomethingWithB(b);
  33.     }
  34.  
  35.     void doSomethingWithB (BaseB<LIB> *b) {
  36.         assert(b);
  37.         doSomethingWithB(*b);
  38.     }
  39.  
  40.     virtual void doSomethingWithB (BaseB<LIB> &b) = 0;
  41. };
  42.  
  43. template <typename LIB>
  44. struct BaseB : IfaceB {
  45.     operator BaseB * () override { return this; }
  46. };
  47.  
  48. struct LibFoo {
  49.     class FooA {};
  50.     class FooB {};
  51. };
  52.  
  53. struct ConcreteFooA : BaseA<LibFoo> {
  54.     void doSomethingWithB (BaseB<LibFoo> &) override {
  55.         std::cout << "ConcreteFooA::" << __func__ << '\n';
  56.         //...
  57.     }
  58.  
  59.     LibFoo::FooA a_;
  60. };
  61.  
  62. struct ConcreteFooB : BaseB<LibFoo> {
  63.     LibFoo::FooB b_;
  64. };
  65.  
  66. struct LibBar {
  67.     class BarA {};
  68.     class BarB {};
  69. };
  70.  
  71. struct ConcreteBarA : BaseA<LibBar> {
  72.     void doSomethingWithB (BaseB<LibBar> &) override {
  73.         std::cout << "ConcreteBarA::" << __func__ << '\n';
  74.         //...
  75.     }
  76.  
  77.     LibBar::BarA a_;
  78. };
  79.  
  80. struct ConcreteBarB : BaseB<LibBar> {
  81.     LibBar::BarB b_;
  82. };
  83.  
  84. void
  85. doSomething (IfaceA &a, IfaceB &b)
  86. {
  87.     a.doSomethingWith(b);
  88. }
  89.  
  90. int
  91. main (void)
  92. {
  93.     ConcreteFooA foo_a;
  94.     ConcreteFooB foo_b;
  95.  
  96.     doSomething(foo_a, foo_b);
  97.  
  98.     ConcreteBarA bar_a;
  99.     ConcreteBarB bar_b;
  100.  
  101.     doSomething(bar_a, bar_b);
  102. }
Success #stdin #stdout 0s 3300KB
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ConcreteFooA::doSomethingWithB
ConcreteBarA::doSomethingWithB
https://ideone.com/JjRkfl
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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