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set_flag(+Flag, ++Value)

Succeeds if the flag Flag is successfully set to the value Value.
Flag
Atom.
Value
Atomic or compound term.

Description

Used to set the environment flag Flag to the value Value. The current value of a flag may be returned using get_flag/2. Refer to the specification of get_flag/2 for details about each of the environment flags.

Modes and Determinism

Modules

This predicate is sensitive to its module context (tool predicate, see @/2).

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.

Examples

Success:
   set_flag(gc,verbose).
   set_flag(syntax_option, no_blanks).
   set_flag(syntax_option, not nl_in_quotes).


   % The following example will set a new library path

   [eclipse]: get_flag(library_path,Path),
      set_flag(library_path, ["/home/myuser/mylibs" | Path]).

   Path = ["/usr/local/ECLIPSE/lib"]
   yes.

Fail:
   set_flag(statistics, some).

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

get_flag / 2, env / 0, cd / 1, compile / 1, compile / 2, dynamic / 1, pragma / 1, lib / 1