resultbase.h File Reference

Classes
struct	ResultOkError
struct	TmpErrType< T >
struct	TmpErrType< ResultOk< T > >
class	ResultOk< T >
class	ResultOk< T & >
class	ResultOk< void >
class	ResultMemT< T >
struct	ForwardResultPtr< T >
class	ResultRef< T >
class	ResultBase< T >
class	ResultBase< T & >
class	ResultBase< void >
class	PrivateIsErrorClassHelper< T, IS_OBJECT_REF >
class	PrivateIsErrorClassHelper< T, true >
class	IsErrorClass< T >
class	IsErrorClass< ForwardRef< T > >
class	ResultSuper< RESULT_TYPE, ENABLE >
class	ResultSuper< RESULT_TYPE, typename SFINAEHelper< void, typename RESULT_TYPE::template ResultFunctions< ResultBase< RESULT_TYPE > > >::type >
class	ResultSuper< RESULT_TYPE &, typename SFINAEHelper< void, typename RESULT_TYPE::template ResultFunctions< ResultBase< RESULT_TYPE & > > >::type >
class	Result< RESULT_TYPE >
struct	RemoveResult< T >
struct	RemoveResult< Result< T > >
struct	RemoveResult< ResultOk< T > >
struct	GenericCastMemberTrait< Result< TO >, Result< FROM >, SAFE >
struct	GenericCastTrait< Result< TO >, FROM, SAFE >
struct	GenericCastTrait< Result< TO >, Result< FROM >, SAFE >
class	ResultIteratorFunctions< SUPER >
class	ResultIteratorFunctions< SUPER >::Wrapper

Namespaces
	maxon
	maxon::details

Macros
#define	PRIVATE_MAXON_RBF_SENTINEL(...)
#define	PRIVATE_MAXON_ENABLE_IF_ERROR(TYPE)
#define	PRIVATE_MAXON_ENABLE_IF_ERROR_DUMMY
#define	PRIVATE_MAXON_iferr_scope(T)
#define	PRIVATE_MAXON_iferr_scope_handler()
#define	PRIVATE_MAXON_iferr_return()
#define	PRIVATE_MAXON_iferr_cannot_fail(str)
#define	PRIVATE_MAXON_iferr_ignore_method(str, optionalArg, method, ...)
#define	PRIVATE_MAXON_iferr_ignore(...)
#define	iferr_scope
#define	iferr_scope_handler
#define	iferr_cannot_fail(str)
#define	iferr_ignore(...)
#define	iferr_scope_result
#define	iferr_return
#define	iferr_throw(ERR)

Typedefs
template<typename T >
using	ResultPtr = ResultMemT< T * >

Enumerations
enum class	ERROR_OK { VALUE }
enum class	ERROR_FAILED { VALUE }
enum class	ERROR_TYPE {   OUT_OF_MEMORY ,   NULLPTR ,   ILLEGAL_ARGUMENT ,   ILLEGAL_STATE ,   NOT_IMPLEMENTED ,   UNRESOLVED ,   UNKNOWN }

Functions
enum maxon::ERROR_OK	MAXON_ENUM_LIST (ERROR_OK)
enum maxon::ERROR_FAILED	MAXON_ENUM_LIST (ERROR_FAILED)
enum maxon::ERROR_TYPE	MAXON_ENUM_LIST (ERROR_TYPE)
const Error *	CreateErrorPtr (MAXON_SOURCE_LOCATION_DECLARATION, ERROR_TYPE type) __attribute__((pure
ThreadReferencedError	CreateError (MAXON_SOURCE_LOCATION_DECLARATION, ERROR_TYPE type)
const Error *	PrivateSystemSetCurrentError (const Error &error)
const Error *	PrivateSystemSetCurrentError (Error &&error)
void	PrivateSetError (Error &dest, const Error *src)
	MAXON_MEMBERTYPE_DETECTOR (IsForwardRef, IsForwardRef, std::false_type)
template<typename T >
MAXON_ATTRIBUTE_FORCE_INLINE auto	operator% (const ResultOk< T > &rv, ThreadReferencedError &err) -> decltype(rv.GetValue())
template<typename T >
MAXON_ATTRIBUTE_FORCE_INLINE T	operator% (ResultOk< T > &&rv, ThreadReferencedError &err)
template<typename T >
MAXON_ATTRIBUTE_FORCE_INLINE T &	operator% (ResultOk< T & > &&rv, ThreadReferencedError &err)
MAXON_ATTRIBUTE_FORCE_INLINE void	operator% (ResultOk< void > &&rv, ThreadReferencedError &err)
template<typename T >
MAXON_ATTRIBUTE_FORCE_INLINE auto	operator% (const ResultOk< T > &rv, maxon::details::ResultOkError &err) -> decltype(rv.GetValue())
template<typename T >
MAXON_ATTRIBUTE_FORCE_INLINE T	operator% (ResultOk< T > &&rv, maxon::details::ResultOkError &err)
template<typename T >
MAXON_ATTRIBUTE_FORCE_INLINE T &	operator% (ResultOk< T & > &&rv, maxon::details::ResultOkError &err)
MAXON_ATTRIBUTE_FORCE_INLINE void	operator% (ResultOk< void > &&rv, maxon::details::ResultOkError &err)
template<typename T >
MAXON_ATTRIBUTE_FORCE_INLINE auto	operator% (const Result< T > &rv, ThreadReferencedError &err) -> decltype(rv.GetValue())
template<typename T >
MAXON_ATTRIBUTE_FORCE_INLINE T	operator% (Result< T > &&rv, ThreadReferencedError &err)
template<typename T >
MAXON_ATTRIBUTE_FORCE_INLINE T &	operator% (const Result< T & > &rv, ThreadReferencedError &err)
template<typename T >
MAXON_ATTRIBUTE_FORCE_INLINE T &	operator% (Result< T & > &&rv, ThreadReferencedError &err)
MAXON_ATTRIBUTE_FORCE_INLINE void	operator% (const Result< void > &rv, ThreadReferencedError &err)
MAXON_ATTRIBUTE_FORCE_INLINE void	operator% (Result< void > &&rv, ThreadReferencedError &err)
template<typename T >
MAXON_ATTRIBUTE_FORCE_INLINE T &&	operator% (ResultMemT< T > &&ptr, ThreadReferencedError &err)
template<typename T >
MAXON_ATTRIBUTE_FORCE_INLINE const T &	operator% (const ResultMemT< T > &ptr, ThreadReferencedError &err)
template<typename T >
MAXON_ATTRIBUTE_FORCE_INLINE T &	operator% (ResultRef< T > ptr, ThreadReferencedError &err)

Variables
	VALUE
static const ERROR_FAILED	FAILED
	OUT_OF_MEMORY
	NULLPTR
	ILLEGAL_ARGUMENT
	ILLEGAL_STATE
	NOT_IMPLEMENTED
	UNRESOLVED
	UNKNOWN
const Error	returns_nonnull

Macro Definition Documentation

PRIVATE_MAXON_RBF_SENTINEL

#define PRIVATE_MAXON_RBF_SENTINEL

(

...

)

PRIVATE_MAXON_ENABLE_IF_ERROR

#define PRIVATE_MAXON_ENABLE_IF_ERROR

(

TYPE

)

PRIVATE_MAXON_ENABLE_IF_ERROR_DUMMY

#define PRIVATE_MAXON_ENABLE_IF_ERROR_DUMMY

PRIVATE_MAXON_iferr_scope

#define PRIVATE_MAXON_iferr_scope

(

T

)

PRIVATE_MAXON_iferr_scope_handler

#define PRIVATE_MAXON_iferr_scope_handler

(

)

PRIVATE_MAXON_iferr_return

#define PRIVATE_MAXON_iferr_return

(

)

PRIVATE_MAXON_iferr_cannot_fail

#define PRIVATE_MAXON_iferr_cannot_fail

(

str

)

PRIVATE_MAXON_iferr_ignore_method

#define PRIVATE_MAXON_iferr_ignore_method	(		str,
			optionalArg,
			method,
			...
	)

PRIVATE_MAXON_iferr_ignore

#define PRIVATE_MAXON_iferr_ignore

(

...

)

iferr_scope

#define iferr_scope

Instead of using iferr you can define an iferr_scope and within this scope call methods which might return an error (and decorate them with the iferr_return attribute). If a method returns with an error iferr_return will forward it.

iferr_scope;
 
FuncA() iferr_return;
FuncB() iferr_return;

iferr_scope_handler

#define iferr_scope_handler

To perform a specific action in case of an error (additional logging, or just to set a breakpoint for debugging) you can replace iferr_scope by an iferr_scope_handler:

iferr_scope_handler
{
  DebugStop("special message");
  return err;
};
 
FuncA() iferr_return;
FuncB() iferr_return;

iferr_scope_handler implicitely defines the error variable 'err'.

iferr_cannot_fail

#define iferr_cannot_fail

(

str

)

If an error cannot occur (because you've ensured this by preallocating resources or the algorithm was designed in such a way, etc.) you might use iferr_cannot_fail with a comment which explans why it can't fail. In debug this will check for errors and invoke DebugStop() to notify you that your code is broken, but in release there are no error checks.

iferr_scope;
BaseArray<Int> array;
 
array.EnsureCapacity(42) iferr_return;
for (Int i = 0; i < GetCapacityCount(); i++)
  array.Append(i) iferr_cannot_fail("Capacity was ensured.");

iferr_ignore

#define iferr_ignore

(

...

)

If for perfomance reasons a piece of code has been very carefully designed in a way that error checking is performed at the very end and that no checks are necessary inbetween you may qualify calls with iferr_ignore and a comment which describes why the error can be ignored.

Note

This should only be used for performance critical code which has been profiled properly and has been reviewed thoroughly.

You might supply an optional second parameter (debug) to cause a DebugStop on error.

BaseArray<Int> array;
const Int CNT = 42;
 
for (Int i = 0; i < CNT; i++)
  array.Append(i) iferr_ignore("Errors are handled after append");
 
if (array.GetCount() != CNT)
  return OutOfMemoryError(MAXON_SOURCE_LOCATION);

iferr_scope_result

#define iferr_scope_result

Use iferr_scope_result in finally blocks to deallocate resources based on the error state.

finally
{
  if (iferr_scope_result == FAILED)
    destructSecond = true;
};

iferr_return

#define iferr_return

The iferr_return macro is the easiest way to introduce error handling. It quickly allows you leave a function as soon as an error occurs. iferr_return requires you to define iferr_scope or iferr_scope_handler once beforehand (preferably at the beginning of your function)

iferr_scope;
...
for (Int i = 0; i < 5; i++)
{
  array.Append(5) iferr_return;
}
UniqueRef<MyClass> obj = UniqueRef<MyClass>::Create() iferr_return;
MyRef ref = MyRef::Create() iferr_return;

iferr_return forwards the error to the calling function. To do this your function must either return Result<T> or use an iferr_scope_handler.
When iferr_return is used within 'for', 'if', 'else' or 'while' those statements must use brackets around their scope, otherwise iferr_return will not be properly executed.

iferr_throw

#define iferr_throw

(

ERR

)

Manually throw an error. Especially useful in combination with iferr_scope_handler to cleanup things in case of errors. Usually you just create error messages and return them in case of a problem like in this example:

static Result<void> DoSomething()
{
  Char* mem = NewMem(Char, 200) iferr_return;
 
  while (true)
  {
    // do something
    ...
    if (FuncA() != 2)
      return IllegalStateError(MAXON_SOURCE_LOCATION, "Invalid return value"_s);
    ...
    if (FuncB() != 40)
      return IllegalStateError(MAXON_SOURCE_LOCATION, "Invalid return value"_s);
    ...
    if (FuncC() != -3)
      return IllegalStateError(MAXON_SOURCE_LOCATION, "Invalid return value"_s);
  }
 
  DeleteMem(mem);
  return OK;
}

The big problem is that in case of an error the allocated chars are nevers freed. Instead of deleting the mem at each possible error point in the algo you can throw the error instead of returning them and then catch the error with iferr_scope_handler and handle the cleanup at a single place like in this example:

static Result<void> DoSomething()
{
  Char* mem = nullptr;
 
  iferr_scope_handler
  {
    DeleteMem(mem); // always guarantee cleanup even in error case
    return err;
  };
 
  mem = NewMem(Char, 200) iferr_return;
 
  while (true)
  {
    // do something
    ...
    if (FuncA() != 2)
      iferr_throw(IllegalStateError(MAXON_SOURCE_LOCATION, "Invalid return value"_s));
    ...
    if (FuncB() != 40)
      iferr_throw(IllegalStateError(MAXON_SOURCE_LOCATION, "Invalid return value"_s));
    ...
    if (FuncC() != -3)
      iferr_throw(IllegalStateError(MAXON_SOURCE_LOCATION, "Invalid return value"_s));
  }
 
  DeleteMem(mem);
  return OK;
}

Variable Documentation

VALUE

VALUE

The single value of this enum.

OUT_OF_MEMORY

OUT_OF_MEMORY

Create an OutOfMemoryError.

NULLPTR

NULLPTR

Create a NullptrError.

ILLEGAL_ARGUMENT

ILLEGAL_ARGUMENT

Create an IllegalArgumentError.

ILLEGAL_STATE

ILLEGAL_STATE

Create an IllegalStateError.

NOT_IMPLEMENTED

NOT_IMPLEMENTED

Create a FunctionNotImplementedError.

UNRESOLVED

UNRESOLVED

Create an UnresolvedError.

UNKNOWN

UNKNOWN

< Create an UnknownError.