H5P_REGISTER1 registers a new property with a property list class. The property will exist in all property list objects of class created after this routine finishes. The name of the property must not already exist, or this routine will fail. The default property value must be provided and all new property lists created with this property will have the property value set to the default value. Any of the callback routines may be set to NULL if they are not needed.

Zero-sized properties are allowed and do not store any data in the property list. These may be used as flags to indicate the presence or absence of a particular piece of information. The default pointer for a zero-sized property may be set to NULL. The property create and close callbacks are called for zero-sized properties, but the set and get callbacks are never called.

The create routine is called when a new property list with this property is being created. The H5P_prp_create_func_t callback function is defined as follows:

typedef herr_t(*H5P_prp_create_func_t)(const char *name,size_t size,void *initial_value);

The parameters to this callback function are defined as follows:

The create routine may modify the value to be set and those changes will be stored as the initial value of the property. If the create routine returns a negative value, the new property value is not copied into the property and the create routine returns an error value.

The set routine is called before a new value is copied into the property. The H5P_prp_set_func_t callback function is defined as follows:

typedef herr_t(*H5P_prp_set_func_t)(hid_t prop_id,const char *name,size_t size,void *new_value);

The parameters to this callback function are defined as follows:

The set routine may modify the value pointer to be set and those changes will be used when setting the property's value. If the set routine returns a negative value, the new property value is not copied into the property and the set routine returns an error value. The set routine will not be called for the initial value, only the create routine will be called.

Note: The set callback function may be useful to range check the value being set for the property or may perform some transformation or translation of the value set. The get callback would then reverse the transformation or translation. A single get or set callback could handle multiple properties by performing different actions based on the property name or other properties in the property list.

The get routine is called when a value is retrieved from a property value. The H5P_prp_get_func_t callback function is defined as follows:

typedef herr_t(*H5P_prp_get_func_t)(hid_t prop_id,const char *name,size_t size,void *value);

The parameters to the callback function are defined as follows:

The get routine may modify the value to be returned from the query and those changes will be returned to the calling routine. If the set routine returns a negative value, the query routine returns an error value.

The delete routine is called when a property is being deleted from a property list. The H5P_prp_delete_func_t callback function is defined as follows:

typedef herr_t(*H5P_prp_delete_func_t)(hid_t prop_id,const char *name,size_t size,void *value);

The parameters to the callback function are defined as follows:

The delete routine may modify the value passed in, but the value is not used by the library when the delete routine returns. If the delete routine returns a negative value, the property list delete routine returns an error value but the property is still deleted.

The copy routine is called when a new property list with this property is being created through a copy operation. The H5P_prp_copy_func_t callback function is defined as follows:

typedef herr_t(*H5P_prp_copy_func_t)(const char *name,size_t size,void *value);

The parameters to the callback function are defined as follows:

The copy routine may modify the value to be set and those changes will be stored as the new value of the property. If the copy routine returns a negative value, the new property value is not copied into the property and the copy routine returns an error value.

The close routine is called when a property list with this property is being closed. The H5P_prp_close_func_t callback function is defined as follows:

typedef herr_t(*H5P_prp_close_func_t)(hid_t prop_id,const char *name,size_t size,void *value);

The parameters to the callback function are defined as follows:

The close routine may modify the value passed in, but the value is not used by the library when the close routine returns. If the close routine returns a negative value, the property list close routine returns an error value but the property list is still closed.

If a C routine that takes a function pointer as an argument is called from within C++ code, the C routine should be returned from normally.

Examples of this kind of routine include callbacks such as H5P_SET_ELINK_CB and H5P_SET_TYPE_CONV_CB and functions such as H5T_CONVERT and H5E_WALK2.

Exiting the routine in its normal fashion allows the HDF5 C library to clean up its work properly. In other words, if the C++ application jumps out of the routine back to the C++ “catch” statement, the library is not given the opportunity to close any temporary data structures that were set up when the routine was called. The C++ application should save some state as the routine is started so that any problem that occurs might be diagnosed.

Success: a non-negative value Failure: a negative value

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