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  1. #include <iostream>
  2. #include <utility>
  3. #include <tuple>
  4.  
  5. bool validate (std::string s) { return !s.empty(); }
  6. bool validate (const void *p) { return p; }
  7.  
  8. template <typename Tuple>
  9. bool validate (Tuple param) {
  10.     if (validate(std::get<0>(param))) return true;
  11.     #ifndef NDEBUG
  12.     std::cout << "Invalid: " << std::get<1>(param) << std::endl;
  13.     std::get<2>(param)();
  14.     #endif
  15.     return false;
  16. }
  17.  
  18. bool validate () { return true; }
  19.  
  20. template <typename T, typename... Params>
  21. bool validate (T param, Params... params) {
  22.     return validate(param) & validate(params...);
  23. }
  24.  
  25. void foo (std::string appPath, std::string appName) {
  26.     bool result
  27.         = validate(
  28.               std::make_tuple(appPath, "ApplicationPath",
  29.                               [&](){ appPath = "defaultPath"; }),
  30.               std::make_tuple(appName, "ApplicationName",
  31.                               [&](){ appName = "defaultName"; })
  32.                    //...
  33.                   );
  34.     if (result) std::cout << "all good!\n";
  35.     else std::cout << "bad param!\n";
  36.  
  37.     std::cout << "path:" << appPath << ", name:" << appName << std::endl;
  38. }
  39.  
  40. int main () {
  41.      foo(std::string(), std::string());
  42.      foo(std::string(), "world");
  43.      foo("Hello", std::string());
  44.      foo("Hello", "world");
  45. }
  46.  
Success #stdin #stdout 0s 3432KB
comments (?)
stdin
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Standard input is empty
stdout
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Invalid: ApplicationPath
Invalid: ApplicationName
bad param!
path:defaultPath, name:defaultName
Invalid: ApplicationPath
bad param!
path:defaultPath, name:world
Invalid: ApplicationName
bad param!
path:Hello, name:defaultName
all good!
path:Hello, name:world
https://ideone.com/50oWu5
language:
C++14 (gcc 8.3)
created:
11 years ago
visibility:
public

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