set_flag(+Flag, ++Value)

Flag

Atom.

Value

Atomic or compound term.

Description

Refer to the specification of get_flag/2 for details about each flag.

The current value(s) of a flag may be returned using get_flag/2.

Modes and Determinism

• set_flag(+, ++) is det

Modules

Exceptions

(4) instantiation fault

Flag and/or Value are not instantiated.

(5) type error

Flag is neither an atom nor a variable.

(5) type error

Value is not of the expected type.

(6) out of range

Flag and/or Value are out of range.

(30) trying to write a read-only flag

Flag is a read-only flag.

(141) unimplemented functionality

Unimplemented setting.

Examples

Set a simple option to a different value:
   ?- set_flag(gc, verbose).

   ?- set_flag(macro_expansion, off).

Add a value to a multi-valued option:
   ?- set_flag(syntax_option, read_floats_as_breals).

Remove a value from a multi-valued option:
   ?- set_flag(syntax_option, not read_floats_as_breals).

Modify the library path:
   ?- get_flag(library_path, OldPath),
      set_flag(library_path, ["/home/myuser/mylibs"|OldPath]).

Error:
   set_flag(X,a).                (Error  4)
   set_flag("a",x).              (Error  5)
   set_flag(blah, a).            (Error  6)
   set_flag(gc,fred).            (Error  6)
   set_flag(version,1).          (Error 30)

See Also