abolish/2

Module: builtins

abolish/1 — remove a procedure from the database
abolish/2 — remove a procedure from the database
abolish/3 — remove a procedure from the database

ISO Standard Predicate

FORMS

abolish(Name/Arity)

abolish(Name, Arity)

abolish(Module, Name, Arity)

DESCRIPTION

For the first two forms, all the clauses for the specified procedure Name/Arity in the current module are removed from the database. The module from which to abolish clauses can be specified by prefixing one of the first two forms with a M:, where M is the module name, or by using the third form (recall that user is the name of the default module). The first two forms are defined in terms of the third using module_closures. The first form is synonymous with the second.

If the module M does not exist, then both M:abolish(Name/Arity) and M:abolish(Name, Arity) throw a procedure existence error. But abolish(M, Name, Arity) succeeds, even though it obviously could not have removed a procedure. (See the last three examples below.)

If module M does exist, but predicate Name/Arity does not exist in M, then all three calls

M:abolish(Name/Arity),  M:abolish(Name, Arity), abolish(M, Name, Arity)

succeed, even though there are no clauses in module M to be removed.

EXAMPLES

?- listing.

% goods:value/2
value(gold,high).
value(mink_coat,high).
value(t_shirt,low).

% goods:electric/1
electric(heater).
electric(iron).

% user:solid/1
solid(door).
solid(floor).

% user:fluid/1
fluid(sand).

yes.

?- user:abolish(solid/1).

yes.
?- listing.

% goods:value/2
value(gold,high).
value(mink_coat,high).
value(t_shirt,low).

% goods:electric/1
electric(heater).
electric(iron).

% user:fluid/1
fluid(sand).

yes.

?- abolish(goods, value, 2).

yes.
?- listing.

% goods:electric/1
electric(heater).
electric(iron).

% user:fluid/1
fluid(sand).

yes.

?- goods:abolish(victim,7).

yes.
?- abolish(goods,victim,7).

yes.
?- goods:abolish(victim/7).

yes.

?- othermodule:abolish(victim,7).
Error: Operation attempted on object of type procedure which does not exist.
Operation attempted on: othermodule:abolish(victim,7).
- Goal:          othermodule:abolish(victim,7)
- Throw pattern: error(
                     existence_error(procedure,
                         othermodule:abolish(victim,7)),
                     [othermodule:abolish(victim,7)])

?- othermodule:abolish(victim/7).
Error: Operation attempted on object of type procedure which does not exist.
Operation attempted on: othermodule:abolish(victim/7).
- Goal:          othermodule:abolish(victim/7)
- Throw pattern: error(existence_error(procedure,othermodule:abolish(*)),
                     [othermodule:abolish(*)])

?- abolish(othermodule,victim,7).
yes.

ERRORS

If Name is not an atom or Arity is not an integer, abolish/2 fails.

SEE ALSO