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  1. #include <iostream>
  2. #include <string>
  3. #include <functional>
  4.  
  5. class Foo
  6. {
  7.   public:
  8.  
  9.     Foo () = default;
  10.     ~Foo () = default;
  11.  
  12.     void set (const std::string & v)
  13.     {
  14.         value = v;
  15.     }
  16.  
  17.     void set ()
  18.     {
  19.         lambda = [](Foo* self)
  20.         {
  21.             return self->value;
  22.         };
  23.     }
  24.  
  25.     std::string get ()
  26.     {
  27.         return lambda(this);
  28.     }
  29.  
  30.  
  31.     std::string value;
  32.     std::function <std::string (Foo*)> lambda;
  33. };
  34.  
  35. int main ()
  36. {
  37.     Foo foo;
  38.  
  39.     foo.set ();
  40.     foo.set ("first");
  41.  
  42.     std::cerr << foo.get () << std::endl; // prints "first"
  43.  
  44.     foo.set ("captures change");
  45.  
  46.     std::cerr << foo.get () << std::endl; // prints "captures change"
  47.  
  48.     Foo foo2 (foo);
  49.     foo2.set ("second");
  50.  
  51.     std::cerr << foo.get () << std::endl; // prints "captures change" (as desired)
  52.     std::cerr << foo2.get () << std::endl; // prints "captures change" (I would want "second" here)
  53.  
  54.     return 0;
  55. }
  56.  
Success #stdin #stdout 0s 3060KB
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https://ideone.com/U9q4y
language:
C++14 (gcc 8.3)
created:
12 years ago
visibility:
public

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