Asserts a clause as the first one for an object dynamic predicate.
When the predicate was not previously declared (using a scope directive), a dynamic predicate declaration is added to the object. In this case, the predicate scope depends on how this method is called:
- The predicate is dynamically declared as private.
- The predicate is dynamically declared as protected.
- The predicate is dynamically declared as public.
Note, however, that dynamically declaring a new predicate requires either a
local assert or the dynamic_declarations
compiler flag set to
allow when the object was created or compiled.
When the predicate indicator for
Head is declared in a
uses/2 or use_module/2 directive, the
clause is asserted in the referenced object or module. When the backend
Prolog compiler supports a module system, the predicate argument can also
be module qualified.
This method may be used to assert clauses for predicates that are not declared dynamic for dynamic objects provided that the predicates are declared in this. This allows easy initialization of dynamically created objects when writing constructors.
Modes and number of proofs¶
asserta(+clause) - one
Headis a variable:
Headis a neither a variable nor a callable term:
Bodycannot be converted to a goal:
Name/Arity, is that of a private predicate:
permission_error(modify, private_predicate, Name/Arity)
Name/Arity, is that of a protected predicate:
permission_error(modify, protected_predicate, Name/Arity)
Name/Arity, is that of a static predicate:
permission_error(modify, static_predicate, Name/Arity)
Name/Arity, does not match a declared predicate and the target object was created or compiled with support for dynamic declaration of predicates turned off:
permission_error(create, predicate_declaration, Name/Arity)
:- category(attributes, implements(attributes_protocol)). :- private(attr_/1). :- dynamic(attr_/1). set_in_this(A, X) :- asserta(attr_(A, X)). set_in_self(A, X) :- ::asserta(attr_(A, X)). ...
:- object(reasoner(_KnowledgeBase_)). :- uses(_KnowledgeBase_, [ foo/1, bar/1 ]). baz(X) :- % compiled as _KnowledgeBase_::assertz(foo(X)) asserta(foo(X)). foobar(Name, Argument) :- Clause =.. [Name, Argument], % runtime resolved to _KnowledgeBase_::assertz(Clause) % when Name is either foo or bar asserta(Clause). ...