1package Config::Std;
2
3our $VERSION = '0.900';
4
5require v5.7.3; # RT#21184
6
7my %global_def_sep;
8my %global_inter_gap;
9
10sub import {
11    my ($package, $opt_ref) = @_;
12    my $caller = caller();
13    $global_def_sep{$caller} = $opt_ref->{def_sep};
14    $global_inter_gap{$caller} = $opt_ref->{def_gap};
15    for my $sub_name (qw( read_config write_config )) {
16        $opt_ref->{$sub_name} ||= $sub_name;
17    }
18    *{$caller.'::'.$opt_ref->{read_config}}  = \&Config::Std::Hash::read_config;
19    *{$caller.'::'.$opt_ref->{write_config}} = \&Config::Std::Hash::write_config;
20}
21
22package Config::Std::Gap;
23use Class::Std;
24{
25    sub serialize { return "\n" }
26    sub update  {}
27    sub extend  {}
28    sub copy_to {}
29}
30
31package Config::Std::Comment;
32use Class::Std;
33{
34    my %text_of : ATTR( :init_arg<text> );
35
36    sub serialize {
37        my ($self) = @_;
38        return $text_of{ident $self};
39    }
40
41    sub append_comment {
42        my ($self, $new_text) = @_;
43        $text_of{ident $self} .= $new_text;
44    }
45
46    sub update  {}
47    sub extend  {}
48    sub copy_to {}
49}
50
51package Config::Std::Keyval;
52use Class::Std;
53{
54    my %key_of      : ATTR( :init_arg<key> :get<key> );
55    my %vals_of     : ATTR;
56    my %deleted_of  : ATTR;
57
58    sub BUILD {
59        my ($self, $ident, $arg_ref) = @_;
60
61        $vals_of{$ident}     = [ { %{$arg_ref} } ];
62    }
63
64    my %SEPARATOR = ( ':' => ': ', '=' => ' = ' );
65
66    use Carp;
67
68    sub serialize {
69        my ($self, $def_sep, $block_name) = @_;
70        my $ident = ident $self;
71
72        return "" if $deleted_of{$ident};
73
74        my ($key, $vals) = ($key_of{$ident}, $vals_of{$ident});
75
76        my $keyspace = q{ } x length($key);
77
78        my $serialization = q{};
79
80        for $n (0..$#{$vals}) {
81            my ($val,$sep,$comm) = @{$vals->[$n]}{qw(val sep comm)};
82
83            my $val_type = ref $val;
84            croak qq{Can't save \L$val_type\E ref as value for key {'$block_name'}{'$key'} (only scalars or array refs)}
85                if $val_type && $val_type ne 'ARRAY';
86
87            $sep = $SEPARATOR{$sep || $def_sep};
88
89            my @vals = $val_type eq 'ARRAY' ? @{$val} : $val;
90            s/ (?!\Z) \n /\n$keyspace$sep/gxms for @vals;
91
92            $serialization .= $comm || q{};
93
94            $serialization .= join q{}, map {"$key$sep$_\n"} @vals;
95        }
96
97        return $serialization;
98    }
99
100    sub update {
101        my ($self, $hash_ref, $updated_ref) = @_;
102        my $ident = ident $self;
103
104        my $key = $key_of{$ident};
105
106        if (!exists $hash_ref->{$key}) {
107            $deleted_of{$ident} = 1;
108        }
109        else {
110            my $val = $hash_ref->{$key};
111            @newvals = ref $val eq 'ARRAY' ? @{$val} : $val;
112            for my $n (0..$#newvals) {
113                $vals_of{$ident}[$n]{val} = $newvals[$n];
114            }
115            splice @{$vals_of{$ident}}, scalar @newvals;
116        }
117
118        $updated_ref->{$key} = 1;
119
120        return 1;
121    }
122
123    sub copy_to {
124        my ($self, $hash_ref)  = @_;
125        my $ident = ident $self;
126        my @vals = map $_->{val}, @{$vals_of{$ident}};
127        $hash_ref->{$key_of{$ident}} = @vals > 1 ? \@vals : $vals[0];
128    }
129
130    sub multivalue {
131        my ($self, $sep, $val, $comm) = @_;
132        push @{$vals_of{ident $self}}, {val=>$val, sep=>$sep, comm=>$comm};
133    }
134}
135
136package Config::Std::Block;
137use Class::Std;
138{
139    my %name_of         : ATTR( :init_arg<name> :get<name> default => '' );
140    my %sep_count_of    : ATTR;
141    my %precomm_of      : ATTR( :init_arg<precomm> default => '' );
142    my %parcomm_of      : ATTR( :init_arg<parcomm> default => '' );
143    my %components_of   : ATTR;
144    my %deleted_of      : ATTR;
145    my %seen            : ATTR;
146    my %is_first        : ATTR( :init_arg<first> default => '' );
147
148    sub BUILD {
149        my ($self, $ident) = @_;
150        @{$sep_count_of{$ident}}{':','='} = (0,0);
151        $components_of{$ident} = [];
152        $seen{$ident} = {};
153    }
154
155    sub copy_to {
156        my ($self, $hash_ref) = @_;
157        my $ident = ident $self;
158
159        my $keyvals = $hash_ref->{$name_of{$ident}} ||= {};
160
161        for my $comp ( @{$components_of{$ident}} ) {
162            $comp->copy_to($keyvals);
163        }
164
165        $hash_ref->{$name_of{$ident}} = $keyvals;
166    }
167
168    sub serialize {
169        my ($self, $first, $caller, $post_gap, $inter_gap) = @_;
170        my $ident = ident $self;
171
172        return q{} if $deleted_of{$ident};
173
174        my $is_anon = $first && length($name_of{$ident}) == 0;
175
176        my $serialization = q{};
177        if (!$is_anon) {
178            $serialization = ($precomm_of{$ident} || q{})
179                           . "[$name_of{$ident}]"
180                           . (defined $parcomm_of{$ident}?$parcomm_of{$ident}:q{})
181                           . "\n";
182        }
183
184        my $gds = $global_def_sep{$caller};
185        my $def_sep
186            = defined $gds                                             ? $gds
187            : $sep_count_of{$ident}{':'} >= $sep_count_of{$ident}{'='} ? ':'
188            :                                                            '='
189            ;
190
191        $self->ensure_gap() if $inter_gap && !$is_anon;
192
193        for my $comp ( @{$components_of{$ident}} ) {
194            $serialization .= $comp->serialize($def_sep, $name_of{$ident});
195        }
196
197        return $serialization;
198    }
199
200    sub update {
201        my ($self, $hash_ref, $updated_ref) = @_;
202        my $ident = ident $self;
203
204        if (!defined $hash_ref) {
205            $deleted_of{$ident} = 1;
206            return;
207        }
208
209        for my $comp ( @{$components_of{$ident}} ) {
210            $comp->update($hash_ref, $updated_ref) or next;
211        }
212    }
213
214    sub extend {
215        my ($self, $hash_ref, $updated_ref, $post_gap, $inter_gap) = @_;
216
217        # Only the first occurrence of a block has new keys added...
218        return unless $is_first{ident $self};
219
220        my $first = 1;
221        for my $key ( grep {!$updated_ref->{$_}} keys %{$hash_ref}) {
222            my $value = $hash_ref->{$key};
223            my $separate = ref $value || $value =~ m/\n./xms;
224            $self->ensure_gap() if ($first ? $post_gap : $inter_gap)
225                                    || $separate;
226            $self->add_keyval($key, undef, $hash_ref->{$key});
227            $self->add_gap() if $separate;
228            $first = 0;
229        }
230    }
231
232    sub ensure_gap {
233        my ($self) = @_;
234        my $comp_ref = $components_of{ident $self};
235        return if @{$comp_ref} && $comp_ref->[-1]->isa('Config::Std::Gap');
236        push @{$comp_ref}, Config::Std::Gap->new();
237    }
238
239    sub add_gap {
240        my ($self) = @_;
241        push @{$components_of{ident $self}}, Config::Std::Gap->new();
242    }
243
244    sub add_comment {
245        my ($self, $text) = @_;
246        my $comp_ref = $components_of{ident $self};
247        if ($comp_ref && @{$comp_ref} && $comp_ref->[-1]->isa('Config::Std::Comment') ) {
248            $comp_ref->[-1]->append_comment($text);
249        }
250        else {
251            push @{$comp_ref}, Config::Std::Comment->new({text=>$text});
252        }
253    }
254
255    sub add_keyval {
256        my ($self, $key, $sep, $val, $comm) = @_;
257        my $ident = ident $self;
258
259        $sep_count_of{$ident}{$sep}++ if $sep;
260
261        my $seen = $seen{$ident};
262
263        if ($seen->{$key}) {
264            $seen->{$key}->multivalue($sep, $val, $comm);
265            return;
266        }
267
268        my $keyval
269            = Config::Std::Keyval->new({key=>$key, sep=>$sep, val=>$val, comm=>$comm});
270        push @{$components_of{$ident}}, $keyval;
271        $seen->{$key} = $keyval;
272    }
273}
274
275package Config::Std::Hash;
276use Class::Std;
277{
278
279    use Carp;
280    use Fcntl ':flock';     # import LOCK_* constants
281
282    my %post_section_gap_for :ATTR;
283    my %array_rep_for        :ATTR;
284    my %filename_for         :ATTR;
285
286    sub write_config (\[%$];$) {
287        my ($hash_ref, $filename) = @_;
288        $hash_ref = ${$hash_ref} if ref $hash_ref eq 'REF';
289
290        $filename = $filename_for{$hash_ref} if @_<2;
291
292        croak "Missing filename for call to write_config()"
293            unless $filename;
294
295        my $caller = caller;
296
297        my $inter_gap
298            = exists $global_inter_gap{$caller} ? $global_inter_gap{$caller}
299            :                                      1;
300        my $post_gap
301            = $post_section_gap_for{$hash_ref}
302            || (defined $global_inter_gap{$caller} ? $global_inter_gap{$caller}
303                                                   : 1
304               );
305
306        # Update existing keyvals in each block...
307        my %updated;
308        for my $block ( @{$array_rep_for{$hash_ref}} ) {
309            my $block_name = $block->get_name();
310            $block->update($hash_ref->{$block_name}, $updated{$block_name}||={});
311        }
312
313        # Add new keyvals to the first section of block...
314        for my $block ( @{$array_rep_for{$hash_ref}} ) {
315            my $block_name = $block->get_name();
316            $block->extend($hash_ref->{$block_name}, $updated{$block_name},
317                           $post_gap, inter_gap
318                          );
319        }
320
321        # Add new blocks at the end...
322        for my $block_name ( sort grep {!$updated{$_}} keys %{$hash_ref} ) {
323            my $block = Config::Std::Block->new({name=>$block_name});
324            my $subhash = $hash_ref->{$block_name};
325            my $first = 1;
326            for my $key ( keys %{$subhash} ) {
327                if (!defined $subhash->{$key}) {
328                    croak "Can't save undefined value for key {'$block_name'}{'$key'} (only scalars or array refs)";
329                }
330                my $value = $subhash->{$key};
331                my $separate = ref $value || $value =~ m/\n./xms;
332                $block->ensure_gap() if ($first ? $post_gap : $inter_gap)
333                                     || $separate;
334                $block->add_keyval($key, undef, $value);
335                $block->add_gap() if $separate;
336                $first = 0;
337            }
338            $block->ensure_gap();
339            push @{$array_rep_for{$hash_ref}}, $block;
340        }
341
342        open my $fh, '>', $filename
343            or croak "Can't open config file '$filename' for writing (\L$!\E)";
344
345        flock($fh,LOCK_EX|LOCK_NB)
346            || croak "Can't write to locked config file '$filename'"
347                if ! ref $filename;
348
349        my $first = 1;
350        for my $block ( @{$array_rep_for{$hash_ref}} ) {
351            print {$fh} $block->serialize($first, scalar caller, $post_gap);
352            $first = 0;
353        }
354
355        flock($fh,LOCK_UN) if ! ref $filename;
356
357        return 1;
358    }
359
360    sub read_config ($\[%$]) {
361        my ($filename, $var_ref, $opt_ref) = @_;
362        my $var_type = ref($var_ref) || q{};
363        my $hash_ref;
364        if ($var_type eq 'SCALAR' && !defined ${$var_ref} ) {
365            ${$var_ref} = $hash_ref = {};
366        }
367        elsif ($var_type eq 'HASH') {
368            $hash_ref = $var_ref;
369        }
370        else {
371            croak q{Scalar second argument to 'read_config' must be empty};
372        }
373
374        bless $hash_ref, 'Config::Std::Hash';
375
376        my $blocks = $array_rep_for{$hash_ref}
377                   = _load_config_for($filename, $hash_ref);
378
379        for my $block ( @{$blocks} ) {
380            $block->copy_to($hash_ref);
381        }
382
383        $filename_for{$hash_ref} = $filename;
384
385        # Remove initial empty section if no data...
386        if (!keys %{ $hash_ref->{q{}} }) {
387            delete $hash_ref->{q{}};
388        }
389
390        return 1;
391    }
392
393    sub _load_config_for {
394        my ($filename, $hash_ref) = @_;
395
396        open my $fh, '<', $filename
397            or croak "Can't open config file '$filename' (\L$!\E)";
398        flock($fh,LOCK_SH|LOCK_NB)
399            || croak "Can't read from locked config file '$filename'"
400                if !ref $filename;
401        my $text = do{local $/; <$fh>};
402        flock($fh,LOCK_UN) if !ref $filename;
403
404        my @config_file = Config::Std::Block->new({ name=>q{}, first=>1 });
405        my $comment = q{};
406        my %seen;
407
408        # Start tracking whether section markers have gaps after them...
409        $post_section_gap_for{$hash_ref} = 0;
410
411        for ($text) {
412            pos = 0;
413            while (pos() < length() ) {
414                # Gap...
415                if (m/\G (?: [^\S\n]* (?:\n|\z)+)/gcxms) {
416                    ### Found gap
417                    $config_file[-1]->add_comment($comment) if $comment;
418                    $config_file[-1]->add_gap();
419                    $comment = q{};
420                }
421
422                # Comment...
423                elsif (m/\G (\s* [#;] [^\n]* (?:\n|\z) )/gcxms) {
424                    ### Found comment: $1
425                    $comment .= $1;
426                }
427
428                # Block...
429                elsif (m/\G ([^\S\n]*) [[]  ( [^]\n]* ) []] ( ([^\S\n]*) [#;] [^\n]* )? [^\S\n]* (?:\n|\z)/gcxms) {
430                    my ($pre, $name, $parcomm, $ws) = ($1, $2, $3, $4);
431                    ### Found block: $name
432                    if ($parcomm) {
433                        $pre = 2 + length($pre) + length($name) + length($ws);
434                        if (m/\G ( (?: \n? [ ]{$pre,} [#] [^\n]* )+ )/gcxms) {
435                            $parcomm .= "\n$1";
436                        }
437                    }
438                    push @config_file,
439                            Config::Std::Block->new({
440                                name    => $name,
441                                precomm => $comment,
442                                parcomm => $parcomm,
443                                first   => !$seen{$name}++,
444                            });
445                    $comment = q{};
446
447                    # Check for trailing gap...
448                    $post_section_gap_for{$hash_ref}
449                        += m/\G (?= [^\S\n]* (?:\n|\z) )/xms ? +1 : -1;
450                }
451
452                # Key/value...
453                elsif (m/\G [^\S\n]* ([^=:\n]+?) [^\S\n]* ([:=] [^\S\n]*) ([^\n]*) (?:\n|\z)/gcxms) {
454                    my ($key, $sep, $val) = ($1, $2, $3);
455
456                    my $pure_sep = $sep;
457                    $pure_sep =~ s/\s*//g;
458
459                    # Continuation lines...
460                    my $continued = 0;
461                    while (m/\G [^\S\n]* \Q$sep\E ([^\n]*) (?:\n|\z) /gcxms
462                       ||  m/\G [^\S\n]* \Q$pure_sep\E ([^\n]*) (?:\n|\z) /gcxms
463                    ) {
464                        $val .= "\n$1";
465                        $continued = 1;
466                    }
467
468                    $val =~ s/\A \s*|\s* \z//gxms if !$continued;
469
470                    ### Found kv: $key, $val
471
472                    $config_file[-1]->add_keyval($key, $pure_sep, $val,
473                    $comment); $comment = q{}; }
474
475                # Mystery...
476                else {
477                    my ($problem) = m/\G ([^\n]{10,40}|.{10}) /gcxms;
478                    die "Error in config file '$filename' near:\n\n\t$problem\n";
479                }
480            }
481        }
482
483        return \@config_file;
484    }
485
486}
487
488
4891; # Magic true value required at end of module
490__END__
491
492=head1 NAME
493
494Config::Std - Load and save configuration files in a standard format
495
496
497=head1 VERSION
498
499This document describes Config::Std version 0.900
500
501
502=head1 SYNOPSIS
503
504    use Config::Std;
505
506    # Load named config file into specified hash...
507    read_config 'demo2.cfg' => my %config;
508
509    # Extract the value of a key/value pair from a specified section...
510    $config_value = $config{Section_label}{key};
511
512    # Change (or create) the value of a key/value pair...
513    $config{Other_section_label}{other_key} = $new_val;
514
515    # Update the config file from which this hash was loaded...
516    write_config %config;
517
518    # Write the config information to another file as well...
519    write_config %config, $other_file_name;
520
521
522=head1 DESCRIPTION
523
524This module implements yet another damn configuration-file system.
525
526The configuration language is deliberately simple and limited, and the
527module works hard to preserve as much information (section order,
528comments, etc.) as possible when a configuration file is updated.
529
530The whole point of Config::Std is to encourage use of one standard layout
531and syntax in config files. Damian says "I could have gotten away with it, I would have
532only allowed one separator. But it proved impossible to choose between C<:> and C<=>
533(half the people I asked wanted one, half wanted the other)."
534Providing round-trip file re-write is the spoonful of sugar to help the medicine go down.
535The supported syntax is within the general INI file family
536
537See Chapter 19 of "Perl Best Practices" (O'Reilly, 2005)
538for more detail on the
539rationale for this approach.
540
541=head2 Configuration language
542
543The configuration language is a slight extension of the Windows INI format.
544
545=head3 Comments
546
547A comment starts with a C<#> character (Perl-style) or a C<;> character
548(INI-style), and runs to the end of the same line:
549
550    # This is a comment
551
552    ; Ywis, eke hight thilke
553
554Comments can be placed almost anywhere in a configuration file, except inside
555a section label, or in the key or value of a configuration variable:
556
557    # Valid comment
558    [ # Not a comment, just a weird section label ]
559
560    ; Valid comment
561    key: value  ; Not a comment, just part of the value
562
563NOTE BENE -- that last is a BAD EXAMPLE of what is NOT supported.
564This module supports full-line comments only, not on same line with semantic content.
565
566=head3 Sections
567
568A configuration file consists of one or more I<sections>, each of which is
569introduced by a label in square brackets:
570
571    [SECTION1]        # Almost anything is a valid section label
572
573    [SECTION 2]       # Internal whitespace is allowed (except newlines)
574
575    [%^$%^&!!!]       # The label doesn't have to be alphanumeric
576
577    [ETC. ETC. AS MANY AS YOU WANT]
578
579The only restriction on section labels is that they must be by
580themselves on a single line (except for any surrounding whitespace or
581trailing comments), and they cannot contain the character C<]>.
582
583Every line after a given section label until the next section label (or
584the end of the config file) belongs to the given section label. If no
585section label is currently in effect, the current section has an empty
586label. In other words, there is an implicit:
587
588    []                # Label is the empty string
589
590at the start of each config file.
591
592=head3 Configuration variables
593
594Each non-empty line within a section must consist of the specification of a
595I<configuration variable>. Each such variable consists of a key and a string
596value. For example:
597
598    name: George
599     age: 47
600
601    his weight! : 185
602
603The key consists of every character (including internal whitespace) from
604the start of the line until the key/value separator. So, the previous
605example declares three keys: C<'name'>, C<'age'>, and C<'his weight!'>.
606
607Note that whitespace before and after the key is removed. This makes it easier
608to format keys cleanly:
609
610           name : George
611            age : 47
612    his weight! : 185
613
614The key/value separator can be either a colon (as above) or an equals sign,
615like so:
616
617           name= George
618            age=  47
619    his weight! = 185
620
621Both types of separators can be used in the same file, but neither can
622be used as part of a key. Newlines are not allowed in keys either.
623
624When writing out a config file, Config::Std tries to preserve whichever
625separator was used in the original data (if that data was read
626in). New data
627(created by code not parsed by C<read_config>)
628is written back with a colon as its default separator,
629unless you specify the only other separator value C<'='> when the module is loaded:
630
631    use Config::Std { def_sep => '=' };
632
633Note that this does not change read-in parsing,
634does not change punctuation for values that were parsed,
635and will not allow values other than C<'='> or C<':'>.
636
637Everything from the first non-whitespace character after the separator,
638up to the end of the line, is treated as the value for the config variable.
639So all of the above examples define the same three values: C<'George'>,
640C<'47'>, and C<'185'>.
641
642In other words, any whitespace immediately surrounding the separator
643character is part of the separator, not part of the key or value.
644
645Note that you can't put a comment on the same line as a configuration
646variable. The C<# etc.> is simply considered part of the value:
647
648    [Delimiters]
649
650    block delims:    { }
651    string delims:   " "
652    comment delims:  # \n
653
654You can comment a config var on the preceding or succeeding line:
655
656    [Delimiters]
657
658    # Use braces to delimit blocks...
659    block delims:    { }
660
661    # Use double quotes to delimit strings
662
663    string delims:   " "
664
665    # Use octothorpe/newline to delimit comments
666    comment delims:  # \n
667
668
669=head3 Multi-line configuration values
670
671A single value can be continued over two or more lines. If the line
672immediately after a configuration variable starts with the separator
673character used in the variable's definition, then the value of the
674variable continues on that line. For example:
675
676    address: 742 Evergreen Terrace
677           : Springfield
678           : USA
679
680The newlines then form part of the value, so the value specified in the
681previous example is: C<S<"742 Evergreen Terrace\nSpringfield\nUSA">>
682
683Note that the second and subsequent lines of a continued value are considered
684to start where the whitespace after the I<original> separator finished, not
685where the whitespace after their own separator finishes. For example, if the
686previous example had been:
687
688    address: 742 Evergreen Terrace
689           :   Springfield
690           :     USA
691
692then the value would be:
693
694    "742 Evergreen Terrace\n  Springfield\n    USA"
695
696If a continuation line has less leading whitespace that the first line:
697
698    address:   742 Evergreen Terrace
699           :  Springfield
700           : USA
701
702it's treated as having no leading whitespace:
703
704    "742 Evergreen Terrace\nSpringfield\nUSA"
705
706
707=head3 Multi-part configuration values
708
709If the particular key appears more than once in the same section, it is
710considered to be part of the same configuration variable. The value of
711that configuration value is then a list, containing all the individual
712values for each instance of the key. For example, given the definition:
713
714    cast: Homer
715    cast: Marge
716    cast: Lisa
717    cast: Bart
718    cast: Maggie
719
720the corresponding value of the C<'cast'> configuration variable is:
721C<S<['Homer', 'Marge', 'Lisa', 'Bart', 'Maggie']>>
722
723Individual values in a multi-part list can also be multi-line (see
724above). For example, given:
725
726    extras: Moe
727          : (the bartender)
728
729    extras: Smithers
730          : (the dogsbody)
731
732the value for the C<'extras'> config variable is:
733C<S<["Moe\n(the bartender)", "Smithers\n(the dogsbody)"]>>
734
735
736=head2 Internal representation
737
738Each section label in a configuration file becomes a top-level hash key whe
739the configuration file is read in. The corresponding value is a nested hash
740reference.
741
742Each configuration variable's key becomes a key in that nested hash reference.
743Each configuration variable's value becomes the corresponding value in that nested hash reference.
744
745Single-line and multi-line values become strings. Multi-part values become
746references to arrays of strings.
747
748For example, the following configuration file:
749
750    # A simple key (just an identifier)...
751    simple : simple value
752
753    # A more complex key (with whitespace)...
754    more complex key : more complex value
755
756    # A new section...
757    [MULTI-WHATEVERS]
758
759    # A value spread over several lines...
760    multi-line : this is line 1
761               : this is line 2
762               : this is line 3
763
764    # Several values for the same key...
765    multi-value: this is value 1
766    multi-value: this is value 2
767    multi-value: this is value 3
768
769would be read into a hash whose internal structure looked like this:
770
771    {
772       # Default section...
773       '' => {
774          'simple'           => 'simple value',
775          'more complex key' => 'more complex value',
776       },
777
778       # Named section...
779       'MULTI-WHATEVERS' => {
780            'multi-line'  => "this is line 1\nthis is line 2\nthis is line 3",
781
782            'multi-value' => [ 'this is value 1',
783                               'this is value 2',
784                               'this is value 3'
785                             ],
786        }
787    }
788
789
790=head1 INTERFACE
791
792The following subroutines are exported automatically whenever the module is
793loaded...
794
795=over
796
797=item C<< read_config($filename => %config_hash) >>
798
799=item C<< read_config($filename => $config_hash_ref) >>
800
801=item C<< read_config($string_ref => %config_hash_or_ref) >>
802
803The C<read_config()> subroutine takes two arguments: the filename of a
804configuration file, and a variable into which the contents of that
805configuration file are to be loaded.
806
807If the variable is a hash, then the configuration sections and their
808key/value pairs are loaded into nested subhashes of the hash.
809
810If the variable is a scalar with an undefined value, a reference to an
811anonymous hash is first assigned to that scalar, and that hash is then
812filled as described above.
813
814The subroutine returns true on success, and throws an exception on failure.
815
816If you pass a reference to the string as the first argument to
817C<read_config()> it uses that string as the source of the config info.
818For example:
819
820	use Config::Std;
821
822	# here we load the config text to a scalar
823	my $cfg = q{
824	[Section 1]
825	attr1 = at
826	attr2 = bat
827
828	[Section 2]
829	attr3 = cat
830	};
831
832	# here we parse the config from that scalar by passing a reference to it.
833	read_config( \$cfg, my %config );
834
835	use Data::Dumper 'Dumper';
836	warn Dumper [ \%config ];
837
838
839=item C<< write_config(%config_hash => $filename) >>
840
841=item C<< write_config($config_hash_ref => $filename) >>
842
843=item C<write_config(%config_hash)>
844
845=item C<write_config($config_hash_ref)>
846
847The C<write_config()> subroutine takes two arguments: the hash or hash
848reference containing the configuration data to be written out to disk,
849and an optional filename specifying which file it is to be written to.
850
851The data hash must conform to the two-level structure described earlier:
852with top-level keys naming sections and their values being references to
853second-level hashes that store the keys and values of the configuartion
854variables. If the structure of the hash differs from this, an exception is
855thrown.
856
857If a filename is also specified, the subroutine opens that file
858and writes to it. It no filename is specified, the subroutine uses the
859name of the file from which the hash was originally loaded using
860C<read_config()>. It no filename is specified and the hash I<wasn't>
861originally loaded using C<read_config()>, an exception is thrown.
862
863The subroutine returns true on success and throws and exception on failure.
864
865=back
866
867If necessary (typically to avoid conflicts with other modules), you can
868have the module export its two subroutines with different names by
869loading it with the appropriate options:
870
871    use Config::Std { read_config => 'get_ini', write_config => 'update_ini' };
872
873    # and later...
874
875    get_ini($filename => %config_hash);
876
877    # and later still...
878
879    update_ini(%config_hash);
880
881You can also control how much spacing the module puts between single-
882line values when they are first written to a file, by using the
883C<def_gap> option:
884
885    # No empty line between single-line config values...
886    use Config::Std { def_gap => 0 };
887
888    # An empty line between all single-line config values...
889    use Config::Std { def_gap => 1 };
890
891Regardless of the value passed for C<def_gap>, new multi-line values are
892always written with an empty line above and below them. Likewise, values
893that were previously read in from a file are always written back with
894whatever spacing they originally had.
895
896=head1 DIAGNOSTICS
897
898=over
899
900=item Can't open config file '%s' (%s)
901
902You tried to read in a configuration file, but the file you specified
903didn't exist. Perhaps the filepath you specified was wrong. Or maybe
904your application didn't have permission to access the file you specified.
905
906=item Can't read from locked config file '$filename'
907
908You tried to read in a configuration file, but the file you specified
909was being written by someone else (they had a file lock active on it).
910Either try again later, or work out who else is using the file.
911
912=item Scalar second argument to 'read_config' must be empty
913
914You passed a scalar variable as the destination into C<read_config()>
915was supposed to load a configuration file, but that variable already had
916a defined value, so C<read_config()> couldn't autovivify a new hash for
917you. Did you mean to pass the subroutine a hash instead of a scalar?
918
919=item Can't save %s value for key '%s' (only scalars or array refs)
920
921You called C<write_config> and passed it a hash containing a
922configuration variable whose value wasn't a single string, or a list of
923strings. The configuration file format supported by this module only
924supports those two data types as values. If you really need to store
925other kinds of data in a configuration file, you should consider using
926C<Data::Dumper> or C<YAML> instead.
927
928=item Missing filename in call to write_config()
929
930You tried to calll C<write_config()> with only a configuration hash, but that
931hash wasn't originally loaded using C<read_config()>, so C<write_config()> has
932no idea where to write it to. Either make sure the hash you're trying to save
933was originally loaded using C<read_config()>, or else provide an explicit
934filename as the second argument to C<write_config()>.
935
936=item Can't open config file '%s' for writing (%s)
937
938You tried to update or create a configuration file, but the file you
939specified could not be opened for writing (for the reason given in the
940parentheses). This is often caused by incorrect filepaths or lack of
941write permissions on a directory.
942
943=item Can't write to locked config file '%s'
944
945You tried to update or create a configuration file, but the file you
946specified was being written at the time by someone else (they had a file
947lock active on it). Either try again later, or work out who else is
948using the file.
949
950=back
951
952
953=head1 CONFIGURATION AND ENVIRONMENT
954
955Config::Std requires no configuration files or environment variables.
956(To do so would be disturbingly recursive.)
957
958
959=head1 DEPENDENCIES
960
961This module requires the Class::Std module (available from the CPAN)
962
963
964=head1 INCOMPATIBILITIES
965
966Those variants of INI file dialect supporting partial-line comment are incompatible.
967(This is the price of keeping comments when re-writing.)
968
969
970=head1 BUGS AND LIMITATIONS
971
972=over
973
974=item Loading on demand
975
976If you attempt to load C<read_config()> and C<write_config()>
977at runtime with C<require>, you can not rely upon the prototype
978to convert a regular hash to a reference. To work around this,
979you must explicitly pass a reference to the config hash.
980
981    require Config::Std;
982    Config::Std->import;
983
984    my %config;
985    read_config($file, \%config);
986    write_config(\%config, $file);
987
988=item Windows line endings on Unix/Linux (RT#21547/23550)
989
990If the config file being read contains carriage returns and line feeds
991at the end of each line rather than just line feeds (i.e. the standard
992Windows file format, when read on a machine expecting POSIX file format),
993Config::Std emits an error with embedded newline.
994
995Workaround is match file line-endings to locale.
996
997This will be fixed in 1.000.
998
999
1000=item leading comment vanishes (RT#24597,)
1001
1002A comment before the first section is not always retained on write-back, if the '' default section is empty.
1003
1004=item 00write.t test 5 fails on perl5.8.1 (RT#17425)
1005
1006Due to an incompatible change in v5.8.1 partially reversed in v5.8.2, hash key randomisation can cause test to fail in that one version of Perl. Workaround is export environment variable PERL_HASH_SEED=0.
1007
1008=back
1009
1010Please report any bugs or feature requests to
1011C<bug-config-std@rt.cpan.org>, or through the web interface at
1012L<http://rt.cpan.org>.
1013
1014
1015=head1 AUTHOR
1016
1017Damian Conway  C<< <DCONWAY@cpan.org> >>
1018Maintainers
1019Bill Ricker    C<< <BRICKER@cpan.org> >>
1020Tom Metro      C<< <tmetro@cpan.org> >>
1021
1022=head1 LICENCE AND COPYRIGHT
1023
1024Copyright (c) 2005, Damian Conway C<< <DCONWAY@cpan.org> >>.
1025Copyright (c) 2011, D.Conway, W.Ricker C<< <BRICKER@cpan.org> >> All rights reserved.
1026
1027This module is free software; you can redistribute it and/or
1028modify it under the same terms as Perl itself.
1029
1030
1031=head1 DISCLAIMER OF WARRANTY
1032
1033BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
1034FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN
1035OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
1036PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER
1037EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
1038WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE
1039ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH
1040YOU. SHOULD THE SOFTWARE PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL
1041NECESSARY SERVICING, REPAIR, OR CORRECTION.
1042
1043IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
1044WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
1045REDISTRIBUTE THE SOFTWARE AS PERMITTED BY THE ABOVE LICENCE, BE
1046LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL,
1047OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE
1048THE SOFTWARE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING
1049RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A
1050FAILURE OF THE SOFTWARE TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF
1051SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
1052SUCH DAMAGES.
1053