1AppConfig::State(3) User Contributed Perl Documentation AppConfig::State(3)
2
6 AppConfig::State - application configuration state
7
9 use AppConfig::State;
10 my $state = AppConfig::State->new(\%cfg);
12 $state->define("foo"); # very simple variable definition
14 $state->define("bar", \%varcfg); # variable specific configuration
15 $state->define("foo|bar=i@"); # compact format
16 $state->set("foo", 123); # trivial set/get examples
18 $state->get("foo");
19 $state->foo(); # shortcut variable access
21 $state->foo(456); # shortcut variable update
22
24 AppConfig::State is a Perl5 module to handle global configuration
25 variables for perl programs. It maintains the state of any number of
26 variables, handling default values, aliasing, validation, update
27 callbacks and option arguments for use by other AppConfig::* modules.
28 AppConfig::State is distributed as part of the AppConfig bundle.
30
32 USING THE AppConfig::State MODULE
33 To import and use the AppConfig::State module the following line should
34 appear in your Perl script:
35 use AppConfig::State;
37 The AppConfig::State module is loaded automatically by the new()
39 constructor of the AppConfig module.
40 AppConfig::State is implemented using object-oriented methods. A new
42 AppConfig::State object is created and initialised using the new()
43 method. This returns a reference to a new AppConfig::State object.
44 my $state = AppConfig::State->new();
46 This will create a reference to a new AppConfig::State with all
48 configuration options set to their default values. You can initialise
49 the object by passing a reference to a hash array containing
50 configuration options:
51 $state = AppConfig::State->new( {
53 CASE => 1,
54 ERROR => \&my_error,
55 } );
56 The new() constructor of the AppConfig module automatically passes all
58 parameters to the AppConfig::State new() constructor. Thus, any global
59 configuration values and variable definitions for AppConfig::State are
60 also applicable to AppConfig.
61 The following configuration options may be specified.
63 CASE
65 Determines if the variable names are treated case sensitively. Any
66 non-zero value makes case significant when naming variables. By
67 default, CASE is set to 0 and thus "Variable", "VARIABLE" and
68 "VaRiAbLe" are all treated as "variable".
69 CREATE
71 By default, CREATE is turned off meaning that all variables
72 accessed via set() (which includes access via shortcut such as
73 "$state->variable($value)" which delegates to set()) must
74 previously have been defined via define(). When CREATE is set to
75 1, calling set($variable, $value) on a variable that doesn't exist
76 will cause it to be created automatically.
77 When CREATE is set to any other non-zero value, it is assumed to be
79 a regular expression pattern. If the variable name matches the
80 regex, the variable is created. This can be used to specify
81 configuration file blocks in which variables should be created, for
82 example:
83 $state = AppConfig::State->new( {
85 CREATE => '^define_',
86 } );
87 In a config file:
89 [define]
91 name = fred # define_name gets created automatically
92 [other]
94 name = john # other_name doesn't - warning raised
95 Note that a regex pattern specified in CREATE is applied to the
97 real variable name rather than any alias by which the variables may
98 be accessed.
99 PEDANTIC
101 The PEDANTIC option determines what action the configuration file
102 (AppConfig::File) or argument parser (AppConfig::Args) should take
103 on encountering a warning condition (typically caused when trying
104 to set an undeclared variable). If PEDANTIC is set to any true
105 value, the parsing methods will immediately return a value of 0 on
106 encountering such a condition. If PEDANTIC is not set, the method
107 will continue to parse the remainder of the current file(s) or
108 arguments, returning 0 when complete.
109 If no warnings or errors are encountered, the method returns 1.
111 In the case of a system error (e.g. unable to open a file), the
113 method returns undef immediately, regardless of the PEDANTIC
114 option.
115 ERROR
117 Specifies a user-defined error handling routine. When the handler
118 is called, a format string is passed as the first parameter,
119 followed by any additional values, as per printf(3C).
120 DEBUG
122 Turns debugging on or off when set to 1 or 0 accordingly.
123 Debugging may also be activated by calling _debug() as an object
124 method ("$state->_debug(1)") or as a package function
125 (AppConfig::State::_debug(1)), passing in a true/false value to set
126 the debugging state accordingly. The package variable
127 $AppConfig::State::DEBUG can also be set directly.
128 The _debug() method returns the current debug value. If a new
130 value is passed in, the internal value is updated, but the previous
131 value is returned.
132 Note that any AppConfig::File or App::Config::Args objects that are
134 instantiated with a reference to an App::State will inherit the
135 DEBUG (and also PEDANTIC) values of the state at that time.
136 Subsequent changes to the AppConfig::State debug value will not
137 affect them.
138 GLOBAL
140 The GLOBAL option allows default values to be set for the DEFAULT,
141 ARGCOUNT, EXPAND, VALIDATE and ACTION options for any subsequently
142 defined variables.
143 $state = AppConfig::State->new({
145 GLOBAL => {
146 DEFAULT => '<undef>', # default value for new vars
147 ARGCOUNT => 1, # vars expect an argument
148 ACTION => \&my_set_var, # callback when vars get set
149 }
150 });
151 Any attributes specified explicitly when a variable is defined will
153 override any GLOBAL values.
154 See "DEFINING VARIABLES" below which describes these options in
156 detail.
157 DEFINING VARIABLES
159 The "define()" function is used to pre-declare a variable and specify
160 its configuration.
161 $state->define("foo");
163 In the simple example above, a new variable called "foo" is defined. A
165 reference to a hash array may also be passed to specify configuration
166 information for the variable:
167 $state->define("foo", {
169 DEFAULT => 99,
170 ALIAS => 'metavar1',
171 });
172 Any variable-wide GLOBAL values passed to the new() constructor in the
174 configuration hash will also be applied. Values explicitly specified
175 in a variable's define() configuration will override the respective
176 GLOBAL values.
177 The following configuration options may be specified
179 DEFAULT
181 The DEFAULT value is used to initialise the variable.
182 $state->define("drink", {
184 DEFAULT => 'coffee',
185 });
186 print $state->drink(); # prints "coffee"
188 ALIAS
190 The ALIAS option allows a number of alternative names to be
191 specified for this variable. A single alias should be specified as
192 a string. Multiple aliases can be specified as a reference to an
193 array of alternatives or as a string of names separated by vertical
194 bars, '|'. e.g.:
195 # either
197 $state->define("name", {
198 ALIAS => 'person',
199 });
200 # or
202 $state->define("name", {
203 ALIAS => [ 'person', 'user', 'uid' ],
204 });
205 # or
207 $state->define("name", {
208 ALIAS => 'person|user|uid',
209 });
210 $state->user('abw'); # equivalent to $state->name('abw');
212 ARGCOUNT
214 The ARGCOUNT option specifies the number of arguments that should
215 be supplied for this variable. By default, no additional arguments
216 are expected for variables (ARGCOUNT_NONE).
217 The ARGCOUNT_* constants can be imported from the AppConfig module:
219 use AppConfig ':argcount';
221 $state->define('foo', { ARGCOUNT => ARGCOUNT_ONE });
223 or can be accessed directly from the AppConfig package:
225 use AppConfig;
227 $state->define('foo', { ARGCOUNT => AppConfig::ARGCOUNT_ONE });
229 The following values for ARGCOUNT may be specified.
231 ARGCOUNT_NONE (0)
233 Indicates that no additional arguments are expected. If the
234 variable is identified in a confirguration file or in the
235 command line arguments, it is set to a value of 1 regardless of
236 whatever arguments follow it.
237 ARGCOUNT_ONE (1)
239 Indicates that the variable expects a single argument to be
240 provided. The variable value will be overwritten with a new
241 value each time it is encountered.
242 ARGCOUNT_LIST (2)
244 Indicates that the variable expects multiple arguments. The
245 variable value will be appended to the list of previous values
246 each time it is encountered.
247 ARGCOUNT_HASH (3)
249 Indicates that the variable expects multiple arguments and that
250 each argument is of the form "key=value". The argument will be
251 split into a key/value pair and inserted into the hash of
252 values each time it is encountered.
253 ARGS
255 The ARGS option can also be used to specify advanced command line
256 options for use with AppConfig::Getopt, which itself delegates to
257 Getopt::Long. See those two modules for more information on the
258 format and meaning of these options.
259 $state->define("name", {
261 ARGS => "=i@",
262 });
263 EXPAND
265 The EXPAND option specifies how the AppConfig::File processor
266 should expand embedded variables in the configuration file values
267 it reads. By default, EXPAND is turned off (EXPAND_NONE) and no
268 expansion is made.
269 The EXPAND_* constants can be imported from the AppConfig module:
271 use AppConfig ':expand';
273 $state->define('foo', { EXPAND => EXPAND_VAR });
275 or can be accessed directly from the AppConfig package:
277 use AppConfig;
279 $state->define('foo', { EXPAND => AppConfig::EXPAND_VAR });
281 The following values for EXPAND may be specified. Multiple values
283 should be combined with vertical bars , '|', e.g. "EXPAND_UID |
284 EXPAND_VAR").
285 EXPAND_NONE
287 Indicates that no variable expansion should be attempted.
288 EXPAND_VAR
290 Indicates that variables embedded as $var or $(var) should be
291 expanded to the values of the relevant AppConfig::State
292 variables.
293 EXPAND_UID
295 Indicates that '~' or '~uid' patterns in the string should be
296 expanded to the current users ($<), or specified user's home
297 directory. In the first case, "~" is expanded to the value of
298 the "HOME" environment variable. In the second case, the
299 "getpwnam()" method is used if it is available on your system
300 (which it isn't on Win32).
301 EXPAND_ENV
303 Inidicates that variables embedded as ${var} should be expanded
304 to the value of the relevant environment variable.
305 EXPAND_ALL
307 Equivalent to "EXPAND_VARS | EXPAND_UIDS | EXPAND_ENVS").
308 EXPAND_WARN
310 Indicates that embedded variables that are not defined should
311 raise a warning. If PEDANTIC is set, this will cause the
312 read() method to return 0 immediately.
313 VALIDATE
315 Each variable may have a sub-routine or regular expression defined
316 which is used to validate the intended value for a variable before
317 it is set.
318 If VALIDATE is defined as a regular expression, it is applied to
320 the value and deemed valid if the pattern matches. In this case,
321 the variable is then set to the new value. A warning message is
322 generated if the pattern match fails.
323 VALIDATE may also be defined as a reference to a sub-routine which
325 takes as its arguments the name of the variable and its intended
326 value. The sub-routine should return 1 or 0 to indicate that the
327 value is valid or invalid, respectively. An invalid value will
328 cause a warning error message to be generated.
329 If the GLOBAL VALIDATE variable is set (see GLOBAL in DESCRIPTION
331 above) then this value will be used as the default VALIDATE for
332 each variable unless otherwise specified.
333 $state->define("age", {
335 VALIDATE => '\d+',
336 });
337 $state->define("pin", {
339 VALIDATE => \&check_pin,
340 });
341 ACTION
343 The ACTION option allows a sub-routine to be bound to a variable as
344 a callback that is executed whenever the variable is set. The
345 ACTION is passed a reference to the AppConfig::State object, the
346 name of the variable and the value of the variable.
347 The ACTION routine may be used, for example, to post-process
349 variable data, update the value of some other dependant variable,
350 generate a warning message, etc.
351 Example:
353 $state->define("foo", { ACTION => \&my_notify });
355 sub my_notify {
357 my $state = shift;
358 my $var = shift;
359 my $val = shift;
360 print "$variable set to $value";
362 }
363 $state->foo(42); # prints "foo set to 42"
365 Be aware that calling "$state->set()" to update the same variable
367 from within the ACTION function will cause a recursive loop as the
368 ACTION function is repeatedly called.
369 DEFINING VARIABLES USING THE COMPACT FORMAT
371 Variables may be defined in a compact format which allows any ALIAS and
372 ARGS values to be specified as part of the variable name. This is
373 designed to mimic the behaviour of Johan Vromans' Getopt::Long module.
374 Aliases for a variable should be specified after the variable name,
376 separated by vertical bars, '|'. Any ARGS parameter should be appended
377 after the variable name(s) and/or aliases.
378 The following examples are equivalent:
380 $state->define("foo", {
382 ALIAS => [ 'bar', 'baz' ],
383 ARGS => '=i',
384 });
385 $state->define("foo|bar|baz=i");
387 READING AND MODIFYING VARIABLE VALUES
389 AppConfig::State defines two methods to manipulate variable values:
390 set($variable, $value);
392 get($variable);
393 Both functions take the variable name as the first parameter and
395 "set()" takes an additional parameter which is the new value for the
396 variable. "set()" returns 1 or 0 to indicate successful or
397 unsuccessful update of the variable value. If there is an ACTION
398 routine associated with the named variable, the value returned will be
399 passed back from "set()". The "get()" function returns the current
400 value of the variable.
401 Once defined, variables may be accessed directly as object methods
403 where the method name is the same as the variable name. i.e.
404 $state->set("verbose", 1);
406 is equivalent to
408 $state->verbose(1);
410 Without parameters, the current value of the variable is returned. If
412 a parameter is specified, the variable is set to that value and the
413 result of the set() operation is returned.
414 $state->age(29); # sets 'age' to 29, returns 1 (ok)
416 VARLIST
418 The varlist() method can be used to extract a number of variables into
419 a hash array. The first parameter should be a regular expression used
420 for matching against the variable names.
421 my %vars = $state->varlist("^file"); # all "file*" variables
423 A second parameter may be specified (any true value) to indicate that
425 the part of the variable name matching the regex should be removed when
426 copied to the target hash.
427 $state->file_name("/tmp/file");
429 $state->file_path("/foo:/bar:/baz");
430 my %vars = $state->varlist("^file_", 1);
432 # %vars:
434 # name => /tmp/file
435 # path => "/foo:/bar:/baz"
436 INTERNAL METHODS
438 The interal (private) methods of the AppConfig::State class are listed
439 below.
440 They aren't intended for regular use and potential users should
442 consider the fact that nothing about the internal implementation is
443 guaranteed to remain the same. Having said that, the AppConfig::State
444 class is intended to co-exist and work with a number of other modules
445 and these are considered "friend" classes. These methods are provided,
446 in part, as services to them. With this acknowledged co-operation in
447 mind, it is safe to assume some stability in this core interface.
448 The _varname() method can be used to determine the real name of a
450 variable from an alias:
451 $varname->_varname($alias);
453 Note that all methods that take a variable name, including those listed
455 below, can accept an alias and automatically resolve it to the correct
456 variable name. There is no need to call _varname() explicitly to do
457 alias expansion. The _varname() method will fold all variables names
458 to lower case unless CASE sensititvity is set.
459 The _exists() method can be used to check if a variable has been
461 defined:
462 $state->_exists($varname);
464 The _default() method can be used to reset a variable to its default
466 value:
467 $state->_default($varname);
469 The _expand() method can be used to determine the EXPAND value for a
471 variable:
472 print "$varname EXPAND: ", $state->_expand($varname), "\n";
474 The _argcount() method returns the value of the ARGCOUNT attribute for
476 a variable:
477 print "$varname ARGCOUNT: ", $state->_argcount($varname), "\n";
479 The _validate() method can be used to determine if a new value for a
481 variable meets any validation criteria specified for it. The variable
482 name and intended value should be passed in. The methods returns a
483 true/false value depending on whether or not the validation succeeded:
484 print "OK\n" if $state->_validate($varname, $value);
486 The _pedantic() method can be called to determine the current value of
488 the PEDANTIC option.
489 print "pedantic mode is ", $state->_pedantic() ? "on" ; "off", "\n";
491 The _debug() method can be used to turn debugging on or off (pass 1 or
493 0 as a parameter). It can also be used to check the debug state,
494 returning the current internal value of $AppConfig::State::DEBUG. If a
495 new debug value is provided, the debug state is updated and the
496 previous state is returned.
497 $state->_debug(1); # debug on, returns previous value
499 The _dump_var($varname) and _dump() methods may also be called for
501 debugging purposes.
502 $state->_dump_var($varname); # show variable state
504 $state->_dump(); # show internal state and all vars
505
507 Andy Wardley, <abw@wardley.org>
508
510 Copyright (C) 1997-2007 Andy Wardley. All Rights Reserved.
511 Copyright (C) 1997,1998 Canon Research Centre Europe Ltd.
513 This module is free software; you can redistribute it and/or modify it
515 under the same terms as Perl itself.
516
518 AppConfig, AppConfig::File, AppConfig::Args, AppConfig::Getopt
519perl v5.34.0 2021-07-22 AppConfig::State(3)