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get_flag(++PredSpec, ?Flag, -Value)

Succeeds if the flag Flag of the procedure specified by PredSpec has the value Value.
Expression of the form Atom/Integer.
Atom or variable.
Atom, integer, compound_term or variable.


Used to get the value Value of the flag Flag of the procedure specified by PredSpec. The values of certain flags may be set using set_flag/3. It can also be used to test if a procedure with a given functor exists or has certain properties.

The possible flags, their values and their meanings are:

    Flags             Values        Description
    auxiliary         on,off        predicate is a
                                    compiler auiliary
    call_type         prolog,       predicate calling
                      external      convention
    debugged          on, off       compiled in
                                    debugging mode
    declared          on, off       predicate was
    defined           on, off       predicate code
    definition_module an atom       where the procedure
                                    is defined
    demon             on, off       predicate is a demon
    deprecated        on, off       predicate is deprecated,
                                    warning on use
    leash             stop,         see below
    mode              pred(Mode1,   the mode of the
                      ...)          predicate
    parallel          on, off       clauses may be exe-
                                    cuted in parallel
    priority          1..12         waking priority
    skip              on, off       procedure will be
                                    traced, but its
                                    children will not
    spy               on, off       procedure has a
    stability         static,       is the procedure
                      dynamic       dynamic?
    tool              on, off       tool property
    type              built-in,     type of predicate
    visibility        local,        module scope
    source_file       an atom       the file where
    source_line       an integer    starting line
                                    number in the file
    source_offset     an integer    byte offset at
                                    which the procedure
                                    definition starts
                                    in its source file
The possible values of leash and their meanings are:

   | Values   Description                               |
   |--------------------------------------------------  |
   | stop     procedure ports are printed and the       |
   |          debugger stops on them                    |
   | print    procedure ports are printed and the       |
   |          debugger does not stop on them            |
   | notrace  procedure ports will not be shown, but    |
   |          its childrens's ports will                |

Modes and Determinism


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

Fail Conditions

Fails if the flag Flag of the procedure specified by PredSpec does not have the value Value, if its value is unknown or if the procedure does not exist


(4) instantiation fault
PredSpec is not instantiated
(5) type error
PredSpec is not an expression of the form Atom/Integer.
(5) type error
Flag is instantiated but not to an atom.
(5) type error
Value is not an atom.


    [eclipse]: get_flag(member/2, F, V),
            printf("%-20s%w\n", [F, V]), fail.

    mode                member(?, ?)
    call_type           prolog
    debugged            off
    declared            on
    autoload            off
    auxiliary           off
    defined             on
    leash               stop
    skip                off
    spy                 off
    start_tracing       off
    stability           static
    tool                off
    type                built_in
    visibility          imported
    priority            2
    demon               off
    parallel            off
    definition_module   sepia_kernel

    get_flag(true/0, defined, off).
    get_flag(undef/0, F, V).
    get_flag(X, spy, on).           (Error 4).
    get_flag("a", spy, on).         (Error 5).

See Also

pred / 1, set_flag / 3, current_module_predicate / 2