The new functions for caching on datatypes are:
| MPI_TYPE_CREATE_KEYVAL(type_copy_attr_fn, type_delete_attr_fn, type_keyval, extra_state) | |
| IN type_copy_attr_fn | copy callback function for type_keyval (function) | 
| IN type_delete_attr_fn | delete callback function for type_keyval (function) | 
| OUT type_keyval | key value for future access (integer) | 
| IN extra_state | extra state for callback functions | 
 
  int MPI_Type_create_keyval(MPI_Type_copy_attr_function *type_copy_attr_fn, MPI_Type_delete_attr_function *type_delete_attr_fn, int *type_keyval, void *extra_state) 
  
 
  MPI_TYPE_CREATE_KEYVAL(TYPE_COPY_ATTR_FN, TYPE_DELETE_ATTR_FN, TYPE_KEYVAL, EXTRA_STATE, IERROR)
 EXTERNAL TYPE_COPY_ATTR_FN, TYPE_DELETE_ATTR_FN
INTEGER TYPE_KEYVAL, IERROR
INTEGER(KIND=MPI_ADDRESS_KIND) EXTRA_STATE 
  
 
  
  static int MPI::Datatype::Create_keyval(MPI::Datatype::Copy_attr_function* type_copy_attr_fn, MPI::Datatype::Delete_attr_function* type_delete_attr_fn, void* extra_state) 
  
  
The argument type_copy_attr_fn may be specified as MPI_TYPE_NULL_COPY_FN or MPI_TYPE_DUP_FN from either C, C++, or Fortran. MPI_TYPE_NULL_COPY_FN is a function that does nothing other than returning flag = 0 and MPI_SUCCESS. MPI_TYPE_DUP_FN is a simple-minded copy function that sets flag = 1, returns the value of attribute_val_in in attribute_val_out, and returns MPI_SUCCESS.
The argument type_delete_attr_fn may be specified as MPI_TYPE_NULL_DELETE_FN from either C, C++, or Fortran. MPI_TYPE_NULL_DELETE_FN is a function that does nothing, other than returning MPI_SUCCESS.
The C callback functions are:
 
  
  typedef int MPI_Type_copy_attr_function(MPI_Datatype oldtype, int type_keyval, void *extra_state, void *attribute_val_in, void *attribute_val_out, int *flag); 
  
and
 
  typedef int MPI_Type_delete_attr_function(MPI_Datatype type, int type_keyval, void *attribute_val, void *extra_state); 
  
  
The Fortran callback functions are:
 
  SUBROUTINE TYPE_COPY_ATTR_FN(OLDTYPE, TYPE_KEYVAL, EXTRA_STATE, ATTRIBUTE_VAL_IN, ATTRIBUTE_VAL_OUT, FLAG, IERROR)
 INTEGER OLDTYPE, TYPE_KEYVAL, IERROR
INTEGER(KIND=MPI_ADDRESS_KIND) EXTRA_STATE,
    ATTRIBUTE_VAL_IN, ATTRIBUTE_VAL_OUT
LOGICAL FLAG 
  
and
 
  SUBROUTINE TYPE_DELETE_ATTR_FN(TYPE, TYPE_KEYVAL, ATTRIBUTE_VAL, EXTRA_STATE, IERROR)
 INTEGER TYPE, TYPE_KEYVAL, IERROR
INTEGER(KIND=MPI_ADDRESS_KIND) ATTRIBUTE_VAL, EXTRA_STATE 
  
The C++ callbacks are:
 
  
  typedef int MPI::Datatype::Copy_attr_function(const MPI::Datatype& oldtype, int type_keyval, void* extra_state, const void* attribute_val_in, void* attribute_val_out, bool& flag); 
  
and
 
  typedef int MPI::Datatype::Delete_attr_function(MPI::Datatype& type, int type_keyval, void* attribute_val, void* extra_state); 
  
  
  
| MPI_TYPE_FREE_KEYVAL(type_keyval) | |
| INOUT type_keyval | key value (integer) | 
 
  int MPI_Type_free_keyval(int *type_keyval) 
  
 
  MPI_TYPE_FREE_KEYVAL(TYPE_KEYVAL, IERROR)
 INTEGER TYPE_KEYVAL, IERROR 
   
 
  static void MPI::Datatype::Free_keyval(int& type_keyval) 
  
| MPI_TYPE_SET_ATTR(type, type_keyval, attribute_val) | |
| INOUT type | datatype to which attribute will be attached (handle) | 
| IN type_keyval | key value (integer) | 
| IN attribute_val | attribute value | 
 
  int MPI_Type_set_attr(MPI_Datatype type, int type_keyval, void *attribute_val) 
  
 
 
  MPI_TYPE_SET_ATTR(TYPE, TYPE_KEYVAL, ATTRIBUTE_VAL, IERROR)
 INTEGER TYPE, TYPE_KEYVAL, IERROR
INTEGER(KIND=MPI_ADDRESS_KIND) ATTRIBUTE_VAL 
   
 
  void MPI::Datatype::Set_attr(int type_keyval, const void* attribute_val) 
  
  
| MPI_TYPE_GET_ATTR(type, type_keyval, attribute_val, flag) | |
| IN type | datatype to which the attribute is attached (handle) | 
| IN type_keyval | key value (integer) | 
| OUT attribute_val | attribute value, unless flag = false | 
| OUT flag | false if no attribute is associated with the key (logical) | 
 
  int MPI_Type_get_attr(MPI_Datatype type, int type_keyval, void *attribute_val, int *flag) 
  
 
  MPI_TYPE_GET_ATTR(TYPE, TYPE_KEYVAL, ATTRIBUTE_VAL, FLAG, IERROR)
 INTEGER TYPE, TYPE_KEYVAL, IERROR
INTEGER(KIND=MPI_ADDRESS_KIND) ATTRIBUTE_VAL
LOGICAL FLAG 
    
 
  bool MPI::Datatype::Get_attr(int type_keyval, void* attribute_val) const 
  
| MPI_TYPE_DELETE_ATTR(type, type_keyval) | |
| INOUT type | datatype from which the attribute is deleted (handle) | 
| IN type_keyval | key value (integer) | 
 
  int MPI_Type_delete_attr(MPI_Datatype type, int type_keyval) 
  
 
  MPI_TYPE_DELETE_ATTR(TYPE, TYPE_KEYVAL, IERROR)
 INTEGER TYPE, TYPE_KEYVAL, IERROR 
    
 
  
  void MPI::Datatype::Delete_attr(int type_keyval)