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1 | package MooseX::ConfigFromFile; |
2 | |
3 | use Moose::Role; |
4 | use MooseX::Types::Path::Class qw( File ); |
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5 | use Try::Tiny qw/ try /; |
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6 | |
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7 | our $VERSION = '0.02'; |
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8 | |
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9 | use Carp qw(croak); |
10 | |
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11 | requires 'get_config_from_file'; |
12 | |
13 | has configfile => ( |
14 | is => 'ro', |
15 | isa => File, |
16 | coerce => 1, |
17 | predicate => 'has_configfile', |
18 | ); |
19 | |
20 | sub new_with_config { |
21 | my ($class, %opts) = @_; |
22 | |
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23 | my $configfile; |
24 | |
25 | if(defined $opts{configfile}) { |
26 | $configfile = $opts{configfile} |
27 | } |
28 | else { |
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29 | my $cfmeta = $class->meta->find_attribute_by_name('configfile'); |
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30 | $configfile = try { $class->configfile }; |
31 | $configfile ||= $cfmeta->default if $cfmeta->has_default; |
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32 | } |
33 | |
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34 | if (defined $configfile) { |
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35 | my $hash = $class->get_config_from_file($configfile); |
36 | |
37 | no warnings 'uninitialized'; |
38 | croak "get_config_from_file($configfile) did not return a hash (got $hash)" |
39 | unless ref $hash eq 'HASH'; |
40 | |
41 | %opts = (%$hash, %opts); |
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42 | } |
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43 | |
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44 | $class->new(%opts); |
45 | } |
46 | |
47 | no Moose::Role; 1; |
48 | |
49 | __END__ |
50 | |
51 | =pod |
52 | |
53 | =head1 NAME |
54 | |
55 | MooseX::ConfigFromFile - An abstract Moose role for setting attributes from a configfile |
56 | |
57 | =head1 SYNOPSIS |
58 | |
59 | ######## |
60 | ## A real role based on this abstract role: |
61 | ######## |
62 | |
63 | package MooseX::SomeSpecificConfigRole; |
64 | use Moose::Role; |
65 | |
66 | with 'MooseX::ConfigFromFile'; |
67 | |
68 | use Some::ConfigFile::Loader (); |
69 | |
70 | sub get_config_from_file { |
71 | my ($class, $file) = @_; |
72 | |
73 | my $options_hashref = Some::ConfigFile::Loader->load($file); |
74 | |
75 | return $options_hashref; |
76 | } |
77 | |
78 | |
79 | ######## |
80 | ## A class that uses it: |
81 | ######## |
82 | package Foo; |
83 | use Moose; |
84 | with 'MooseX::SomeSpecificConfigRole'; |
85 | |
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86 | # optionally, default the configfile: |
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87 | sub configfile { '/tmp/foo.yaml' } |
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88 | |
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89 | # ... insert your stuff here ... |
90 | |
91 | ######## |
92 | ## A script that uses the class with a configfile |
93 | ######## |
94 | |
95 | my $obj = Foo->new_with_config(configfile => '/etc/foo.yaml', other_opt => 'foo'); |
96 | |
97 | =head1 DESCRIPTION |
98 | |
99 | This is an abstract role which provides an alternate constructor for creating |
100 | objects using parameters passed in from a configuration file. The |
101 | actual implementation of reading the configuration file is left to |
102 | concrete subroles. |
103 | |
104 | It declares an attribute C<configfile> and a class method C<new_with_config>, |
105 | and requires that concrete roles derived from it implement the class method |
106 | C<get_config_from_file>. |
107 | |
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108 | Attributes specified directly as arguments to C<new_with_config> supercede those |
109 | in the configfile. |
110 | |
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111 | L<MooseX::Getopt> knows about this abstract role, and will use it if available |
112 | to load attributes from the file specified by the commandline flag C<--configfile> |
113 | during its normal C<new_with_options>. |
114 | |
115 | =head1 Attributes |
116 | |
117 | =head2 configfile |
118 | |
119 | This is a L<Path::Class::File> object which can be coerced from a regular pathname |
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120 | string. This is the file your attributes are loaded from. You can add a default |
121 | configfile in the class using the role and it will be honored at the appropriate time: |
122 | |
123 | has +configfile ( default => '/etc/myapp.yaml' ); |
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124 | |
125 | =head1 Class Methods |
126 | |
127 | =head2 new_with_config |
128 | |
129 | This is an alternate constructor, which knows to look for the C<configfile> option |
130 | in its arguments and use that to set attributes. It is much like L<MooseX::Getopts>'s |
131 | C<new_with_options>. Example: |
132 | |
133 | my $foo = SomeClass->new_with_config(configfile => '/etc/foo.yaml'); |
134 | |
135 | Explicit arguments will overide anything set by the configfile. |
136 | |
137 | =head2 get_config_from_file |
138 | |
139 | This class method is not implemented in this role, but it is required of all subroles. |
140 | Its two arguments are the classname and the configfile, and it is expected to return |
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141 | a hashref of arguments to pass to C<new()> which are sourced from the configfile. |
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142 | |
143 | =head2 meta |
144 | |
145 | The Moose meta stuff, included here because otherwise pod tests fail sometimes |
146 | |
147 | =head1 BUGS |
148 | |
149 | =head1 AUTHOR |
150 | |
151 | Brandon L. Black, E<lt>blblack@gmail.comE<gt> |
152 | |
153 | =head1 LICENSE |
154 | |
155 | This library is free software; you can redistribute it and/or modify |
156 | it under the same terms as Perl itself. |
157 | |
158 | =cut |