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1 | package MooseX::ConfigFromFile; |
2 | |
3 | use Moose::Role; |
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4 | use MooseX::Types::Path::Tiny 'Path'; |
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5 | use MooseX::Types::Moose 'Undef'; |
6 | use Try::Tiny; |
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7 | use Carp qw(croak); |
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8 | use namespace::autoclean; |
9 | |
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10 | requires 'get_config_from_file'; |
11 | |
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12 | # overridable in consuming class or role to provide a default value |
13 | # This is called before instantiation, so it must be a class method, |
14 | # and not depend on any other attributes |
15 | sub _get_default_configfile { } |
16 | |
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17 | has configfile => ( |
18 | is => 'ro', |
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19 | isa => Path|Undef, |
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20 | coerce => 1, |
21 | predicate => 'has_configfile', |
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22 | do { try { require MooseX::Getopt; (traits => ['Getopt']) } }, |
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23 | lazy => 1, |
24 | # it sucks that we have to do this rather than using a builder, but some old code |
25 | # simply swaps in a new default sub into the attr definition |
26 | default => sub { shift->_get_default_configfile }, |
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27 | ); |
28 | |
29 | sub new_with_config { |
30 | my ($class, %opts) = @_; |
31 | |
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32 | my $configfile; |
33 | |
34 | if(defined $opts{configfile}) { |
35 | $configfile = $opts{configfile} |
36 | } |
37 | else { |
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38 | # This would only succeed if the consumer had defined a new configfile |
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39 | # sub to override the generated reader - as suggested in old |
40 | # documentation |
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41 | $configfile = try { $class->configfile }; |
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42 | |
43 | # this is gross, but since a lot of users have swapped in their own |
44 | # default subs, we have to keep calling it rather than calling a |
45 | # builder sub directly - and it might not even be a coderef either |
46 | my $cfmeta = $class->meta->find_attribute_by_name('configfile'); |
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47 | $configfile = $cfmeta->default if not defined $configfile and $cfmeta->has_default; |
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48 | |
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49 | if (ref $configfile eq 'CODE') { |
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50 | $configfile = $configfile->($class); |
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51 | } |
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52 | |
53 | my $init_arg = $cfmeta->init_arg; |
54 | $opts{$init_arg} = $configfile if defined $configfile and defined $init_arg; |
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55 | } |
56 | |
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57 | if (defined $configfile) { |
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58 | my $hash = $class->get_config_from_file($configfile); |
59 | |
60 | no warnings 'uninitialized'; |
61 | croak "get_config_from_file($configfile) did not return a hash (got $hash)" |
62 | unless ref $hash eq 'HASH'; |
63 | |
64 | %opts = (%$hash, %opts); |
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65 | } |
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66 | |
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67 | $class->new(%opts); |
68 | } |
69 | |
70 | no Moose::Role; 1; |
71 | |
72 | __END__ |
73 | |
74 | =pod |
75 | |
76 | =head1 NAME |
77 | |
78 | MooseX::ConfigFromFile - An abstract Moose role for setting attributes from a configfile |
79 | |
80 | =head1 SYNOPSIS |
81 | |
82 | ######## |
83 | ## A real role based on this abstract role: |
84 | ######## |
85 | |
86 | package MooseX::SomeSpecificConfigRole; |
87 | use Moose::Role; |
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88 | |
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89 | with 'MooseX::ConfigFromFile'; |
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90 | |
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91 | use Some::ConfigFile::Loader (); |
92 | |
93 | sub get_config_from_file { |
94 | my ($class, $file) = @_; |
95 | |
96 | my $options_hashref = Some::ConfigFile::Loader->load($file); |
97 | |
98 | return $options_hashref; |
99 | } |
100 | |
101 | |
102 | ######## |
103 | ## A class that uses it: |
104 | ######## |
105 | package Foo; |
106 | use Moose; |
107 | with 'MooseX::SomeSpecificConfigRole'; |
108 | |
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109 | # optionally, default the configfile: |
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110 | sub _get_default_configfile { '/tmp/foo.yaml' } |
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111 | |
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112 | # ... insert your stuff here ... |
113 | |
114 | ######## |
115 | ## A script that uses the class with a configfile |
116 | ######## |
117 | |
118 | my $obj = Foo->new_with_config(configfile => '/etc/foo.yaml', other_opt => 'foo'); |
119 | |
120 | =head1 DESCRIPTION |
121 | |
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122 | This is an abstract role which provides an alternate constructor for creating |
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123 | objects using parameters passed in from a configuration file. The |
124 | actual implementation of reading the configuration file is left to |
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125 | concrete sub-roles. |
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126 | |
127 | It declares an attribute C<configfile> and a class method C<new_with_config>, |
128 | and requires that concrete roles derived from it implement the class method |
129 | C<get_config_from_file>. |
130 | |
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131 | Attributes specified directly as arguments to C<new_with_config> supersede those |
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132 | in the configfile. |
133 | |
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134 | L<MooseX::Getopt> knows about this abstract role, and will use it if available |
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135 | to load attributes from the file specified by the command line flag C<--configfile> |
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136 | during its normal C<new_with_options>. |
137 | |
138 | =head1 Attributes |
139 | |
140 | =head2 configfile |
141 | |
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142 | This is a L<Path::Tiny> object which can be coerced from a regular path |
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143 | string or any object that supports stringification. |
144 | This is the file your attributes are loaded from. You can add a default |
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145 | configfile in the consuming class and it will be honored at the appropriate |
146 | time; see below at L</_get_default_configfile>. |
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147 | |
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148 | If you have L<MooseX::Getopt> installed, this attribute will also have the |
149 | C<Getopt> trait supplied, so you can also set the configfile from the |
150 | command line. |
151 | |
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152 | =head1 Class Methods |
153 | |
154 | =head2 new_with_config |
155 | |
156 | This is an alternate constructor, which knows to look for the C<configfile> option |
157 | in its arguments and use that to set attributes. It is much like L<MooseX::Getopts>'s |
158 | C<new_with_options>. Example: |
159 | |
160 | my $foo = SomeClass->new_with_config(configfile => '/etc/foo.yaml'); |
161 | |
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162 | Explicit arguments will override anything set by the configfile. |
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163 | |
164 | =head2 get_config_from_file |
165 | |
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166 | This class method is not implemented in this role, but it is required of all |
167 | classes or roles that consume this role. |
168 | Its two arguments are the class name and the configfile, and it is expected to return |
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169 | a hashref of arguments to pass to C<new()> which are sourced from the configfile. |
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170 | |
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171 | =head2 _get_default_configfile |
172 | |
173 | This class method returns nothing by default, but can and should be redefined |
174 | in a consuming class to return the default value of the configfile (if not |
175 | passed into the constructor explicitly). |
176 | |
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177 | =head1 COPYRIGHT |
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178 | |
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179 | Copyright (c) - the MooseX::ConfigFromFile "AUTHOR" and "CONTRIBUTORS" as listed below. |
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180 | |
181 | =head1 AUTHOR |
182 | |
183 | Brandon L. Black, E<lt>blblack@gmail.comE<gt> |
184 | |
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185 | =head1 CONTRIBUTORS |
186 | |
187 | =over |
188 | |
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189 | =item Tomas Doran |
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190 | |
191 | =item Karen Etheridge |
192 | |
193 | =item Chris Prather |
194 | |
195 | =item Zbigniew Lukasiak |
196 | |
197 | =back |
198 | |
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199 | =head1 LICENSE |
200 | |
201 | This library is free software; you can redistribute it and/or modify |
202 | it under the same terms as Perl itself. |
203 | |
204 | =cut |