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  1.  
  2. import std.stdio;
  3.  
  4. struct A
  5. {
  6.  
  7.     void set(ref B b)
  8.     {
  9.         myB = &b;
  10.     }
  11.  
  12.     void set(B)
  13.     {
  14.         writeln("Nope.");
  15.     }
  16.  
  17.     void voiceOfB()
  18.     {
  19.         myB.voice();
  20.     }
  21.  
  22.     private:
  23.  
  24.     const(B)* myB;
  25.  
  26. }
  27.  
  28. struct B
  29. {
  30.     this(int v)
  31.     {
  32.         value = v;
  33.     }
  34.  
  35.     ~this()
  36.     {
  37.         value = -1;
  38.     }
  39.  
  40.     void voice() const
  41.     {
  42.         writeln("I am B with value = ", value);
  43.     }
  44.  
  45.     ref A setSelfForA(ref A a)
  46.     {
  47.         a.set(this);
  48.         return a;
  49.     }
  50.  
  51.     int value = 0;
  52. }
  53.  
  54. int main(string[] argv)
  55. {
  56.     A a;
  57.  
  58.     a.set(B()); // no way to pass this value without copying
  59.                 // my guess is to try and keep it safe
  60.                 // but then you get the below case which is possible
  61.                 // maybe it's just an overlooked detail but it is possible currently..
  62.  
  63.     B(42).setSelfForA(a)
  64.          .voiceOfB();
  65.  
  66.     a.voiceOfB();
  67.  
  68.     return 0;
  69. }
Success #stdin #stdout 0s 2688KB
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Standard input is empty
stdout
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Nope.
I am B with value = 42
I am B with value = -1
https://ideone.com/INGSsZ
language:
D (dmd 2.085.0)
created:
7 years ago
visibility:
secret

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