1File::ShareDir(3) User Contributed Perl Documentation File::ShareDir(3)
2
6 File::ShareDir - Locate per-dist and per-module shared files
7
9 use File::SharedDir ':ALL';
10 # Where are distribution-level shared data files kept
12 $dir = dist_dir('File-ShareDir');
13 # Where are module-level shared data files kept
15 $dir = module_dir('File::ShareDir');
16 # Find a specific file in our dist/module shared dir
18 $file = dist_file( 'File-ShareDir', 'file/name.txt');
19 $file = module_file('File::ShareDir', 'file/name.txt');
20 # Like module_file, but search up the inheritance tree
22 $file = class_file( 'Foo::Bar', 'file/name.txt' );
23
25 The intent of File::ShareDir is to provide a companion to
26 Class::Inspector and File::HomeDir, modules that take a process that is
27 well-known by advanced Perl developers but gets a little tricky, and
28 make it more available to the larger Perl community.
29 Quite often you want or need your Perl module (CPAN or otherwise) to
31 have access to a large amount of read-only data that is stored on the
32 file-system at run-time.
33 On a linux-like system, this would be in a place such as /usr/share,
35 however Perl runs on a wide variety of different systems, and so the
36 use of any one location is unreliable.
37 Perl provides a little-known method for doing this, but almost nobody
39 is aware that it exists. As a result, module authors often go through
40 some very strange ways to make the data available to their code.
41 The most common of these is to dump the data out to an enormous Perl
43 data structure and save it into the module itself. The result are
44 enormous multi-megabyte .pm files that chew up a lot of memory
45 needlessly.
46 Another method is to put the data "file" after the __DATA__ compiler
48 tag and limit yourself to access as a filehandle.
49 The problem to solve is really quite simple.
51 1. Write the data files to the system at install time.
53 2. Know where you put them at run-time.
55 Perl's install system creates an "auto" directory for both every
57 distribution and for every module file.
58 These are used by a couple of different auto-loading systems to store
60 code fragments generated at install time, and various other modules
61 written by the Perl "ancient masters".
62 But the same mechanism is available to any dist or module to store any
64 sort of data.
65 Using Data in your Module
67 "File::ShareDir" forms one half of a two part solution.
68 Once the files have been installed to the correct directory, you can
70 use "File::ShareDir" to find your files again after the installation.
71 For the installation half of the solution, see Module::Install and its
73 "install_share" directive.
74
76 "File::ShareDir" provides four functions for locating files and
77 directories.
78 For greater maintainability, none of these are exported by default and
80 you are expected to name the ones you want at use-time, or provide the
81 ':ALL' tag. All of the following are equivalent.
82 # Load but don't import, and then call directly
84 use File::ShareDir;
85 $dir = File::ShareDir::dist_dir('My-Dist');
86 # Import a single function
88 use File::ShareDir 'dist_dir';
89 dist_dir('My-Dist');
90 # Import all the functions
92 use File::ShareDir ':ALL';
93 dist_dir('My-Dist');
94 All of the functions will check for you that the dir/file actually
96 exists, and that you have read permissions, or they will throw an
97 exception.
98 dist_dir
100 # Get a distribution's shared files directory
101 my $dir = dist_dir('My-Distribution');
102 The "dist_dir" function takes a single parameter of the name of an
104 installed (CPAN or otherwise) distribution, and locates the shared data
105 directory created at install time for it.
106 Returns the directory path as a string, or dies if it cannot be located
108 or is not readable.
109 module_dir
111 # Get a module's shared files directory
112 my $dir = module_dir('My::Module');
113 The "module_dir" function takes a single parameter of the name of an
115 installed (CPAN or otherwise) module, and locates the shared data
116 directory created at install time for it.
117 In order to find the directory, the module must be loaded when calling
119 this function.
120 Returns the directory path as a string, or dies if it cannot be located
122 or is not readable.
123 dist_file
125 # Find a file in our distribution shared dir
126 my $dir = dist_file('My-Distribution', 'file/name.txt');
127 The "dist_file" function takes two params of the distribution name and
129 file name, locates the dist dir, and then finds the file within it,
130 verifying that the file actually exists, and that it is readable.
131 The filename should be a relative path in the format of your local
133 filesystem. It will simply added to the directory using File::Spec's
134 "catfile" method.
135 Returns the file path as a string, or dies if the file or the dist's
137 directory cannot be located, or the file is not readable.
138 module_file
140 # Find a file in our module shared dir
141 my $dir = module_file('My::Module', 'file/name.txt');
142 The "module_file" function takes two params of the module name and file
144 name. It locates the module dir, and then finds the file within it,
145 verifying that the file actually exists, and that it is readable.
146 In order to find the directory, the module must be loaded when calling
148 this function.
149 The filename should be a relative path in the format of your local
151 filesystem. It will simply added to the directory using File::Spec's
152 "catfile" method.
153 Returns the file path as a string, or dies if the file or the dist's
155 directory cannot be located, or the file is not readable.
156 class_file
158 # Find a file in our module shared dir, or in our parent class
159 my $dir = class_file('My::Module', 'file/name.txt');
160 The "module_file" function takes two params of the module name and file
162 name. It locates the module dir, and then finds the file within it,
163 verifying that the file actually exists, and that it is readable.
164 In order to find the directory, the module must be loaded when calling
166 this function.
167 The filename should be a relative path in the format of your local
169 filesystem. It will simply added to the directory using File::Spec's
170 "catfile" method.
171 If the file is NOT found for that module, "class_file" will scan up the
173 module's @ISA tree, looking for the file in all of the parent classes.
174 This allows you to, in effect, "subclass" shared files.
176 Returns the file path as a string, or dies if the file or the dist's
178 directory cannot be located, or the file is not readable.
179
181 Bugs should always be submitted via the CPAN bug tracker
182 http://rt.cpan.org/NoAuth/ReportBug.html?Queue=File-ShareDir
184 <http://rt.cpan.org/NoAuth/ReportBug.html?Queue=File-ShareDir>
185 For other issues, contact the maintainer.
187
189 Adam Kennedy <adamk@cpan.org>
190
192 File::HomeDir, Module::Install, Module::Install::Share
193
195 Copyright 2005 - 2008 Adam Kennedy.
196 This program is free software; you can redistribute it and/or modify it
198 under the same terms as Perl itself.
199 The full text of the license can be found in the LICENSE file included
201 with this module.
202perl v5.12.0 2008-07-17 File::ShareDir(3)