clear ( Objects : : : )

Delete an iconic object from the HORUS database.

clear deletes iconic objects, whiuch are no longer needed, from the HORUS database. It should be noted that clear is the only way to delete objects from the database, and hence to reclaim their memory, in all host languages except Smalltalk and C++.

Images and regions are normally used by several iconic objects at the same time (uses less memory!). This has the consequence that a region or an image is only deleted if all objects using it have been deleted.

The operator init_horus can be used to reset the system and clear all remaining iconic objects.


Attention

Regarding the use of local variables: Because only local variables are deleted on exit of a subroutine (or a rule in Prolog), while the HORUS database is not updated, it is necessary to clear local objects before exiting the subroutine. Special care has to be taken if backtracking is possible in Prolog (before reaching the clear statements).


Parameters

Objects (input_object)
object(-array) -> object
Objects to be deleted.


Result

clear returns TRUE if all objects are contained in the HORUS database. If not all objects are valid (e.g., already cleared), an exception is raised, which also clears all valid objects. The operator set_check(::'\~clear':) can be used to suppress the raising of this exception. If the input is empty the behaviour can be set via set_system(::'no_object_result',<Result>:). If necessary, an exception is raised.


Possible Predecessors

obj_def


Possible Successors

close_horus


Alternatives

close_horus, init_horus


See also

obj_def, set_check



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