Class error_code

3rd/asio-1.24.0/include/asio/error_code.hpp:80–177

Class to represent an error code value.

/// Class to represent an error code value.
class error_code
{
public:
  /// Default constructor.
  error_code()
    : value_(0),
      category_(&system_category())
  {
  }

  /// Construct with specific error code and category.
  error_code(int v, const error_category& c)
    : value_(v),
      category_(&c)
  {
  }

  /// Construct from an error code enum.
  template <typename ErrorEnum>
  error_code(ErrorEnum e)
  {
    *this = make_error_code(e);
  }

  /// Clear the error value to the default.
  void clear()
  {
    value_ = 0;
    category_ = &system_category();
  }

  /// Assign a new error value.
  void assign(int v, const error_category& c)
  {
    value_ = v;
    category_ = &c;
  }

  /// Get the error value.
  int value() const
  {
    return value_;
  }

  /// Get the error category.
  const error_category& category() const
  {
    return *category_;
  }

  /// Get the message associated with the error.
  std::string message() const
  {
    return category_->message(value_);
  }

  struct unspecified_bool_type_t
  {