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  1. #include <utility>
  2. #include <iostream>
  3. #include <boost/optional.hpp>
  4.  
  5. template <typename T>
  6. auto trycatch(T t) {
  7.   return [f = std::move(t)](auto&&... args) {
  8.     using rettype = decltype(f(std::forward<decltype(args)>(args)...));
  9.     try {
  10.       return boost::optional<rettype>(f(std::forward<decltype(args)>(args)...));
  11.     }
  12.     catch(...)
  13.     {
  14.       return boost::optional<rettype>{};
  15.     }
  16.  
  17.   };
  18. }
  19.  
  20. int access_resource1()
  21. {
  22.   throw std::runtime_error("");
  23. }
  24.  
  25. int access_resource2()
  26. {
  27.   throw std::runtime_error("");
  28. }
  29.  
  30. int calculate_smth()
  31. {
  32.   constexpr auto default_value = 42;
  33.  
  34.   auto val = trycatch(access_resource1)();
  35.   if(!val)
  36.   {
  37.       val = trycatch(access_resource2)();
  38.   }
  39.  
  40.   if(!val)
  41.   {
  42.       val = default_value;
  43.   }
  44.  
  45.   return *val;
  46. }
  47.  
  48. int main() {
  49.   std::cout << calculate_smth() << std::endl;
  50. }
  51.  
Success #stdin #stdout 0s 3460KB
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Standard input is empty
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42
https://ideone.com/N9Fa1s
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
public

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