[ Development Environment and Global Settings | The ECLiPSe Built-In Predicates | Reference Manual | Alphabetic Index ]

get_flag(?Flag, -Value)

Succeeds if the flag Flag has the value Value.
Flag
Atom or Variable.
Value
Prolog term.

Description

Used to return or check the environment flag Flag with value Value. The environment flags which are read/write may be updated using set_flag/2. The current values of the environment flags are returned by env/0.

The following list details the environment flags:

after_event_timer

Access mode : read/write

Type : Atomic constant real or virtual

Description : Specifies the timer used for event_after/2 and event_after_every/2.

all_dynamic

Access mode : read/write

Type : Atomic constant on or off

Default : off

Description : Specifies whether all clauses compiled are dynamic or not. Mainly for test purposes.

break_level

Access mode : read/write

Type : Integer

Description : Specifies current nesting level of recursive top-level loops.

breal_exceptions

Access mode : read/write

Type : Atomic constant on or off

Default : off

Description : If on, unifying or testing bounded reals for identity raises an 'undecidable comparison of bounded reals' exception in case the comparison is undecidable (i.e. the bounds overlap). If off, bounded reals compare equal when their bounds are equal. This flag does not affect arithmetic comparisons.

coroutine

Access mode : read/write

Type : Atomic constant on or off

Default : configuration dependent

Description : Specifies whether built-in predicates delay or raise instantiation faults.

cwd

Access mode : read/write

Type : String

Description : Specifies the name of the current working directory. May also be set using cd/1 or read using getcwd/1.

debug_compile

Access mode : read/write

Type : Atomic constant on or off

Default : on

Description : Specifies whether clauses are compiled for debugging or not. May be overwritten on a file by file basis using pragma(debug) or pragma(nodebug).

debugging

Access mode : read-only

Type : Atomic constant nodebug, creep, or leap

Default : nodebug

Description : Specifies whether debugging is disabled (nodebug) or enabled. trace/0 sets the creep mode, debug/0 sets the leap mode.

default_language

Access mode : read/write

Type : Atom

Default : eclipse_language

Description : Specifies the source language dialect for modules which are created without an explicit language specification (module/1 directive or the create_module/1). Other possible settings are for example 'iso' or 'sicstus'.

eclipse_info_suffix

Access mode : read

Type : String

Default : ".eci"

Description : Specifies the ECLiPSe information file suffix used when a file is generated by icompile/1. The suffix will be automatically appended to the base file name when the information file is generated.

eclipse_object_suffix

Access mode : read

Type : String

Default : ".eco"

Description : Specifies the ECLiPSe object file suffix used when a file is fcompiled. The suffix will be automatically appended to the file's base name when the object file is generated. When loading a file (e.g. use_module/1, lib/1), the system will try to find an object file before a source file by appending the given suffix before the source suffix(es).

enable_interrupts

Access mode : read/write

Type : Atomic constant on or off

Default : on

Description : If on, interrupts are recognised and processed as they occur. If off, interrupts are entered into a delay queue and processed only when the flag is switched back to on. Interrupts should be disabled only for short periods of time in order to keep the system's interrupt response time short.

extension

Access mode : read-only

Type : Atomic constant.

Default : configuration dependent

Description : Specifies which extensions are available in the system. This flag may contain multiple values and will return them on backtracking.

float_precision

Access mode : read-only

Type : Atomic constant

Default : double

Description : This flag is obsolete. Its value is always double.

gc

Access mode : read/write

Type : Atomic constant on, verbose or off

Default : on

Description : Specifies whether garbage collection is enabled (on), disabled (off) or enabled and reports every collection on log_output (verbose).

gc_policy

Access mode : read/write

Type : Atomic constant adaptive or fixed.

Default : adaptive

Description : This option affects the triggering heuristics of the garbage collector, together with the gc_interval setting. The adaptive policy minimises garbage collection time, while the fixed policy minimises space consumption.

gc_interval

Access mode : read/write

Type : Integer

Default : 1/32 of global stack size, at least 64KB

Description : Specify how often the collector is invoked. Roughly, the argument specifies the minimum number of bytes a program must have newly allocated before a garbage collection is triggered. If the garbage collector runs frequently while reclaiming little space it may make sense to increase gc_interval, thus reducing the number of garbage collections. This is normally only necessary when the gc_policy is set to fixed. With gc_policy set to adaptive, the collection intervals will be adjusted automatically. See also gc_policy setting.

gc_interval_dict

Access mode : read/write

Type : Integer

Default : 960

Description : Specify after how many new dictionary entries the dictionary garbage collector is invoked.

goal_expansion

Access mode : read/write

Type : Atomic constant on or off

Default : on

Description : Specifies whether goal expansion is done by the compiler. This includes compiler inlining and goal macro transformations. Can be disabled for debugging purposes.

hostarch

Access mode : read-only

Type : String

Description : String identifying the host processor and operating system. It is also the name of the machine-dependent subdirectories in the ECLiPSe installation.

hostid

Access mode : read-only

Type : String

Description : The unique identification of the host machine that the system is running on.

hostname

Access mode : read-only

Type : string

Description : The name of the current host machine.

ignore_eof

Access mode : read/write

Type : Atomic constant on or off

Description : Controls whether ECLiPSe can be exited by typing an end-of-file to the toplevel-prompt or whether this is ignored. If ignored, ECLiPSe can be exited by calling halt/0.

installation_directory

Access mode : read-only

Type : string

Description : The name of the toplevel directory of the running ECLiPSe installation. All ECLiPSe library, documentation and other directories are below this one.

last_errno

Access mode : read-only

Type : Integer

Description : The error code that the most recent failed operating system call returned. This should no longer be used because of portability problems, use errno_id/1 instead.

library_path

Access mode : read/write

Type : List of strings

Default : the contents of the user's ECLIPSELIBRARYPATH environment variable, followed by the system library directories

Description : Specifies the list of pathnames used by the system to search for library files. The library path is used by lib/1 for autoloading, and to expand library/1 structures in pathnames.

loaded_library

Access mode : read/write

Type : Atom

Description : Returns the names of the currently loaded libraries. This flag may contain multiple values and will return them on backtracking.

macro_expansion

Access mode : read/write

Type : Atomic constant on or off

Default : on

Description : Specifies whether macro expansion used by the source transformation facility is enabled or disabled. Should be disabled only for debugging purposes.

max_global_trail

Access mode : read-only

Type : Integer

Description : The maximum size in bytes to which the global/trail stack can grow. See also statistics/2.

max_local_control

Access mode : read-only

Type : Integer

Description : The maximum size in bytes to which the global/trail stack can grow. See also statistics/2.

max_predicate_arity

Access mode : read-only

Type : Integer

Default : 255

Description : Returns the maximum number of arguments allowed for an ECLiPSe predicate.

object_suffix

Access mode : read-only

Type : String

Description : Returns the suffix of the external object files that can be loaded using load/1. It is usually "so" for systems that support shared libraries and "o" for the others.

occur_check

Access mode : read/write

Type : Atomic constant on or off

Default : off

Description : If the flag is on, occur check is performed on uncompiled unifications and the compiler generates code for unifications that will perform the occur check when necessary. Note that as ECLiPSe built-ins are compiled with this flag off, so the occur check is never performed with built-ins.

output_mode

Access mode : read/write

Type : String

Default : "QPm"

Description : The value is a control string that is recognised by the %w format of printf/3. This format is used to output results on the toplevel loop and to print debugger trace lines. See also the output_options flag.

output_options

Access mode : read/write

Type : List of structures

Default : [depth(20), attributes(pretty), ...]

Description : The value is an output options list as understood by write_term/2,3. This format is used to output results on the toplevel loop and to print debugger trace lines. This flag is an alternative, more readable representation of the values of the print_depth and output_mode flag. It reflects the values of those flags and will change their values whenever it is changed itself.

pid

Access mode : read-only

Type : Integer

Description : Returns the process identifier of the current ECLiPSe .

ppid

Access mode : read-only

Type : Integer

Description : Returns the process identifier of the current ECLiPSe 's parent process.

prefer_rationals

Access mode : read/write

Type : Atomic constant on or off

Default : off

Description : Specifies if the result of a /-division of two integers gives a rational or a floating point result. Similar for the result of raising an integer to a negative integral power.

print_depth

Access mode : read/write

Type : Integer

Default : 20

Description : Specifies the print depth bound for printing compound terms. It is not taken into account by the output predicates that produce machine-readable output (write_canonical, writeq, etc), but other I/O built-ins obey this flag. Identical to the depth(N) component of the output_options flag.

prolog_suffix

Access mode : read/write

Type : List of strings

Default : ["", ".ecl", ".pl"]

Description : Specifies the Prolog source file suffix(es) used when compiling files or loading libraries. The system tries to find the file by appending the given suffixes in the order provided.

remote_protocol_version

Access mode : read only

Type : Integer

Description : Specifies the version of the protocol which this Eclipse uses to communicate with remotely attached peers. See Embedding and Interfacing Manual: The Remote Interface Protocol.

syntax_option

Access mode : read/write

Type : Atom

Description : Returns the names of the currently enabled syntax options. This flag may contain multiple values and will return them on backtracking. A syntax option is reset using set_flag(syntax_option, not(Flag)). Most compatibility packages affect these flags as well. The following options are available:

atom_subscripts
allow atoms to be followed by subscripts, and parse as subscript/2. Useful for parsing other languages, e.g. FlatZinc.
bar_is_no_atom
disallow the use of an unquoted vertical bar as atom or functor.
based_bignums
Allow base notation even for integers longer than the wordsize (i.e. they are always positive).
blanks_after_sign
ignore blank space between a sign and a number (by default, this space is significant and will lead to the sign being taken as prefix operator rather than the number's sign).
blanks_in_nil
has no effect (obsolete).
curly_args_as_list
Parse terms written as {a,b,c} as {}([a,b,c]) instead of the default {}((a,b,c)).
doubled_quote_is_quote
parse a pair of quotes within a quoted item as one occurrence of the quote within the item. If this option is off (the default), consecutive string-quoted and list-quoted items are parsed as a single (concatenated) item, while consecutive quoted atoms are parsed as consecutive atoms.
general_subscripts
allow atoms, parenthesized subterms and subscripted subterms to be followed by subscripts, and parse as subscript/2. Useful for parsing other languages, e.g. Zinc.
iso_base_prefix
allow binary, octal or hexadecimal numbers to be written with 0b, 0o or 0x prefix respectively, and disallow the base'number notation.
iso_escapes
ISO-Prolog compatible escape sequences within strings and atoms.
limit_arg_precedence
do not allow terms with a precedence higher than 999 as structure arguments, unless parenthesised.
nested_comments
allow bracketed comments to be nested.
nl_in_quotes
allow newlines to occur inside quotes (default).
no_array_subscripts
do not allow array subscript syntax for subscript/2.
no_attributes
disallow the Eclipse specific syntax for variable attributes in curly braces.
no_blanks
do not allow blanks between functor and opening parenthesis (default).
no_curly_arguments
disallow the Eclipse specific syntax for structures with named arguments in curly braces.
read_floats_as_breals
read all floating point numbers as bounded reals rather than as floats. The resulting breal is a small interval enclosing the true value of the number in decimal notation.
var_functor_is_apply
allow variables as functors, and parse a term like X(A,B,C) as apply(X,[A,B,C]).
$VAR
terms of the form '$VAR'(N) are printed in a special way by all the predicates that obey operator declarations (i.e. write, writeq, print and partly printf). This is only provided for compatibility packages: the use of the output options of write_term/2,3 or the format options of printf/2,3 is the preferred way of specifying this behaviour.

tmp_dir

Access mode : read/write

Type : String

Default : configuration dependent (see Description below)

Description : Specifies the temporary directory that ECLiPSe may use for storing temporary data files. Value should be an existing directory (in ECLiPSe's file name syntax) that the user can write to (set_flag/2 will fail otherwise). It is also recommended that the directory should reside on a local disk where the I/O operations are as fast as possible.

By default, this directory is taken from the environment variable ECLIPSETMP if it exist. Otherwise, it is "/tmp" for Unix systems; "//C/Temp" for Windows. If none of these exist, it is set to the current working directory at start up.

toplevel_module

Access mode : read/write

Type : Atom

Default : eclipse

Description : The name of the current top-level module. This is the caller module for all queries entered in the top-level loop. By default, this is also shown in the top-level prompt.

unix_time

Access mode : read-only

Type : Integer

Description : Return the time as given by the UNIX time(3) function, ie. seconds since 00:00:00 GMT, Jan 1 1970.

variable_names

Access mode : read/write

Type : Atomic constant on, off or check_singletons

Default : check_singletons

Description : Controls the ability to retain the source name of variables. This flag affects the reading process only, i.e. when a variable is read (or compiled) with the flag set to on, it will keep its name even when the flag is switched off later. check_singletons is like on but additionally the compiler emits warnings about source variables which occur only once in a clause and whose name does not start with an underscore. The source variable names are being created during the term input if this flag is not off, and then they are kept independently of the value of this flag.

version

Access mode : read-only

Type : Atom

Description : Returns the current version number of ECLiPSe .

version_as_list

Access mode : read-only

Type : List of integers

Description : Returns a list of integers, starting with your ECLiPSe system's major version number, and ending with its build number. Note that this list can be used for lexicographic comparison, e.g. [5,3,17] @>= [5,3] or [5,3,17] @>= [5,1,24].

worker

Access mode : read-only

Type : Integer

Description : In a parallel session it returns a positive number, identifying the worker on which the flag inquiry was executed. In a sequential session 0 is returned.

workers

Access mode : read/write

Type : A structure Host:N, where Host is an atom and N integer

Description : In a parallel session it returns a positive number for N, which is the number of active workers on a given host Host. If Host is a variable, it is bound to the host name where this predicate is executed.

workerids

Access mode : read-only

Type : A structure Host:ActiveList+AsleepList, where Host is an atom and ActiveList and AsleepList are integer lists

Description : In a parallel session it returns the workerid lists of of both active and asleep workers on a given host Host. If Host is a variable, it is bound to the host name where this predicate is executed.

wm_window

Access mode : read/write

Type : Atomic constant on or off

Description : In a parallel session this flag tells if the window interface for the worker manager is on or off.

Modes and Determinism

Modules

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

Exceptions

(5) type error
Flag is neither an atom nor variable.

Examples

Success:
   [eclipse]: get_flag(gc, X).
   X = on

   yes.
   [eclipse]: get_flag(loaded_library, L).

   L = lists     More? (;)

   L = development_support     More? (;)
   yes.

Error:
   get_flag(1,X).           (Error 5)



See Also

set_flag / 2, env / 0, errno_id / 1