Add a clause, as the last clause, to a loaded module. The first argument must be the name of a module currently loaded, not the filename of the file in the module. The second argument of this predicate is, if it is a valid term, added after all the other predicates with the same functor and arity.
The clause to be added must have been declared dynamic. The dynamic/1 or dynamic/2 predicates can be used as compile directives or as normal built-in predicates.
see also: abolish/1 abolish/2 asserta/1 assertz/1 asserta/2 dynamic/1 dynamic/2 retract/1 retract/2 set_active_module/0 set_active_module/1
| Examples | |
| assertz( data, computer ). | adds the fact 'computer' to the module 'data' after all other clauses of 'computer' with no arguments |
| assertz( data, test(I) :- do_something(I) ). | the complete predicate test(I) :- do_something(I) is added to the module 'data' after all other test/1 predicates |
| dynamic(data, hoi/1), assertz(data, hoi(arg)). | declare hoi/1 as dynamic in the module 'data' and assert the term 'hoi' to that same module |
| Exceptions | |
| The first argument is a variable | an instantiation_error exception is thrown |
| The first argument Arg is not an atom | a type_error(atom, Arg) exception is thrown |
| No module with the specified Name exists | an existence_error(module, Name) exception is thrown. |
| Clause is a variable | an instantiation_error exception is thrown because the argument is an empty variable |
| Head is variable | an instantiation_error exception is thrown because the head of the clause is a variable |
| Head is neither a variable nor a predication (=a well formed head of a clause term) | a type_error(callable, Head) exception is thrown |
| Body of the clause_term is not a well formed body_term | a type_error(callable, Body) exception is thrown |
| The predicate indicator Pred of the head of the clause_term is that of a static procedure | a permission_error(modify, static_procedure, Pred) exception is thrown |
| asserta(test). %there is no active module | the exception existence_error(active_module) is thrown, this exception is not defined in the ISO Prolog standard |