stx::SpanReport Class Reference

#include <report.h>

Detailed Description

SpanReport is an error-report type containing a reference to an error-string stating the cause of the error from the error type of a Result<T, E>.

When to use SpanReport against FixedReport

• When the error types contain the string description of the errors themselves and you can get a reference to the error.

TIP: SpanReport is named after std::span as it is only a type-erased reference-view of the error string.

Constructing a SpanReport for your error type

NOTE: character literals (i.e. "A STRING") have static storage duration and live throughout the program, constructing a SpanReport with them just forwards a reference to them, it is safe to do this)

namespace net{

  enum class Error {
      ConnectionError,
      ServerClosed,
      ServerUnreachable
  };

};

SpanReport operator>>(ReportQuery, net::Error const& err) noexcept {
  switch(err){
         case net::Error::ConnectionError:
           return SpanReport("Connection error occurred");
         case net::Error::ServerClosed:
           return SpanReport("Server closed unexpectedly");
         case net::Error::ServerUnreachable:
           return SpanReport("Server was unreachable");
   }
 }

namespace net{

     class Error {

          // returns a reference to the error string
          std::string const & what() const noexcept;


           // returns a string_view to the error string
          std::string_view better_what() const noexcept;


           // returns a const string_view reference of the error
          std::string_view const& best_what() const noexcept;


          // `dangerous_what` creates a new string and returns it, totally
          // dangerous as a constructor for `SpanReport` because
          // `SpanReport` binds a reference to its constructor argument
          // which in this case is a temporary and will outlive the
          // `SpanReport` if the `SpanReport` is returned from the report
          query
          // below.
          //
          std::string dangerous_what() const noexcept;
      };

};



SpanReport operator>>(ReportQuery, net::Error const& err) noexcept {
  return SpanReport(err.what());
}

Exception-safety

Ensure to not throw exceptions.

Constructor & Destructor Documentation

SpanReport() [1/5]

constexpr stx::SpanReport::SpanReport ( )

inlinenoexcept

SpanReport() [2/5]

constexpr stx::SpanReport::SpanReport ( const char *  str, size_t  size  )

inlinenoexcept

size: string size excluding null-terminator

SpanReport() [3/5]

constexpr stx::SpanReport::SpanReport ( std::string_view const &  str )

inlineexplicitnoexcept

SpanReport() [4/5]

constexpr stx::SpanReport::SpanReport ( SpanReport const &  )

defaultnoexcept

SpanReport() [5/5]

constexpr stx::SpanReport::SpanReport ( SpanReport &&  )

defaultnoexcept

~SpanReport()

stx::SpanReport::~SpanReport ( )

defaultnoexcept

Member Function Documentation

operator=() [1/2]

constexpr SpanReport& stx::SpanReport::operator= ( SpanReport const &  )

defaultnoexcept

operator=() [2/2]

constexpr SpanReport& stx::SpanReport::operator= ( SpanReport &&  )

defaultnoexcept

what()

constexpr std::string_view stx::SpanReport::what ( ) const

inlinenoexcept

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The documentation for this class was generated from the following file:

• include/stx/report.h