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  1. #include <iostream>
  2.  
  3. #define A_WITH_SHOWPATH
  4.  
  5.  
  6. #if 1 // helpers
  7. struct PainterPath { };
  8. class PathVisual
  9. {
  10. protected:
  11.     PainterPath *mpPath;
  12.     PathVisual(PainterPath *pPath) : mpPath(pPath) { }
  13. public:
  14.     virtual void setVisible() = 0;
  15.     PainterPath* Path() const { return mpPath; }
  16. };
  17. class PathGraphic : public PathVisual
  18. {
  19. public:
  20.     PathGraphic(PainterPath *p) : PathVisual(p) { }
  21.     virtual void setVisible() override { std::cout << "show graphic\n"; } // would display path graphic
  22. };
  23. class PathWidget : public PathVisual
  24. {
  25. public:
  26.     PathWidget(PainterPath *p) : PathVisual(p) { }
  27.     virtual void setVisible() override { std::cout << "show widget\n"; } // would display path widget
  28. };
  29. #endif // helpers
  30.  
  31.  
  32.  
  33. class A
  34. {
  35. #ifdef A_WITH_SHOWPATH
  36. private:
  37.     std::string mPath;
  38. public:
  39.     void setPath(std::string const &path) {
  40.         mPath = path;
  41.         std::cout << "path set to '" << mPath << "'\n";
  42.         showPath();
  43.     }
  44.  
  45.     virtual void showPath() = 0; // to be called from outside, supposed to display mPath
  46. #endif	
  47. };
  48.  
  49. class B : public A
  50. {
  51. protected:
  52.     PainterPath *mpPath;
  53.     B(PainterPath *pPath) : mpPath(pPath) { }
  54. public:
  55.     virtual void showPath() = 0; // to be called from outside
  56. };
  57.  
  58. class C_g : public B {
  59.     PathGraphic *mpGraphic;
  60. public:
  61.     C_g(PathGraphic *pGraphic) : B(pGraphic->Path()), mpGraphic(pGraphic) { }
  62.  
  63.     virtual void showPath() override {
  64.         mpGraphic->setVisible();
  65.     }
  66. };
  67.  
  68. class C_w : public B {
  69.     PathWidget *mpWidget;
  70. public:
  71.     C_w(PathWidget *pWidget) : B(pWidget->Path()), mpWidget(pWidget) { }
  72.     virtual void showPath() override {
  73.         mpWidget->setVisible();
  74.     }
  75. };
  76.  
  77.  
  78. int main() {
  79.     PainterPath p;
  80.     PathGraphic pg(&p);
  81.     PathWidget pw(&p);
  82.     B* b_g = new C_g(&pg);
  83.     B* b_w = new C_w(&pw);
  84.  
  85.     std::cout << "Should say 'show graphic':\n";
  86.     b_g->showPath();
  87.     std::cout << "---------------------------\n";
  88.     std::cout << "Should say 'show widget':\n";
  89.     b_w->showPath();
  90.     std::cout << "---------------------------\n";
  91.  
  92.  
  93. #ifdef A_WITH_SHOWPATH
  94.     std::cout << "Should say \"path set to 'Test'\", but not 'show graphic':\n";
  95.     b_g->setPath("Test");
  96.     std::cout << "# Calling setPath(\"/root\") on a B pointer now also displays the PainterPath, which is not the intended behavior.\n";
  97.     std::cout << "---------------------------\n";
  98. #endif
  99.  
  100.  
  101.     return 0;
  102. }
  103.  
Success #stdin #stdout 0s 3460KB
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Standard input is empty
stdout
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Should say 'show graphic':
show graphic
---------------------------
Should say 'show widget':
show widget
---------------------------
Should say "path set to 'Test'", but not 'show graphic':
path set to 'Test'
show graphic
# Calling setPath("/root") on a B pointer now also displays the PainterPath, which is not the intended behavior.
---------------------------
https://ideone.com/6q0cPD
language:
C++14 (gcc 8.3)
created:
7 years ago
visibility:
public

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