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A custom no-value policy

If you want your basic_outcome<> or basic_result<> instances to call std::abort() whenever .value() is called on an object that does not contain a value, or .error() is called on an object that does not contain an error, you will need to define your own no-value policy as follows:

struct abort_policy : outcome::policy::base
{
  template <class Impl> static constexpr void wide_value_check(Impl &&self)
  {
    if(!base::_has_value(std::forward<Impl>(self)))
      std::abort();
  }

  template <class Impl> static constexpr void wide_error_check(Impl &&self)
  {
    if(!base::_has_error(std::forward<Impl>(self)))
      std::abort();
  }

  template <class Impl> static constexpr void wide_exception_check(Impl &&self)
  {
    if(!base::_has_exception(std::forward<Impl>(self)))
      std::abort();
  }
};
View this code on Github

All policies ought to inherit from base in order to provide your policy implementation with the internal policy API for accessing and manipulating result and outcome state.

Once the policy is defined, you have to specify it when providing your own basic_outcome specialization:

template <typename T>
using strictOutcome =  //
outcome::basic_outcome<T, std::error_code, std::exception_ptr, abort_policy>;
View this code on Github

Last revised: February 08, 2019 at 22:18:08 UTC


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