Error
=====

A flexible error result type.

.. admonition:: Info

   To use declarations from this page, include the ``<essence/error.hpp>`` header.

.. cpp:namespace-push:: essence

.. cpp:class:: error

   A flexible error type, great for use with :cpp:expr:`std::expected`.
   
   .. cpp:function:: error::error(std::string msg, i32 n = 1)

   .. cpp:function:: template<typename... Args> \
                     error::error(i32 n, std::string_view msg, Args&&... args)

      Constructor using :cpp:expr:`std::format` arguments.

   .. cpp:function:: std::string message() const

      Get a copy of the error message string.

   .. cpp:function:: error& message(std::string_view msg)

      Setter for the error message.

   .. cpp:function:: template<typename... Args> \
                     error& message(std::string_view msg, Args&&... args)

      Setter for the error message, with :cpp:expr:`std::format` arguments.

   .. cpp:function:: i32 number() const

      Get the error number.

   .. cpp:function:: error& number(i32 n)

      Setter for the error number.

   .. cpp:function:: void die() const noexcept

      Prints the error message and terminates, marked with the
      ``[[noreturn]]`` attribute.

   .. cpp:function:: constexpr operator bool() const noexcept

      Implicit boolean conversion; evaluates to true only when the
      error number is ``-5``, which is the default value.