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File::ShareDir(3)	       User Contributed Perl Documentation		File::ShareDir(3)

NAME
       File::ShareDir - Locate per-dist and per-module shared files

SYNOPSIS
	 use File::ShareDir ':ALL';

	 # Where are distribution-level shared data files kept
	 $dir = dist_dir('File-ShareDir');

	 # Where are module-level shared data files kept
	 $dir = module_dir('File::ShareDir');

	 # Find a specific file in our dist/module shared dir
	 $file = dist_file(  'File-ShareDir',  'file/name.txt');
	 $file = module_file('File::ShareDir', 'file/name.txt');

	 # Like module_file, but search up the inheritance tree
	 $file = class_file( 'Foo::Bar', 'file/name.txt' );

DESCRIPTION
       The intent of File::ShareDir is to provide a companion to Class::Inspector and
       File::HomeDir, modules that take a process that is well-known by advanced Perl developers
       but gets a little tricky, and make it more available to the larger Perl community.

       Quite often you want or need your Perl module (CPAN or otherwise) to have access to a
       large amount of read-only data that is stored on the file-system at run-time.

       On a linux-like system, this would be in a place such as /usr/share, however Perl runs on
       a wide variety of different systems, and so the use of any one location is unreliable.

       Perl provides a little-known method for doing this, but almost nobody is aware that it
       exists. As a result, module authors often go through some very strange ways to make the
       data available to their code.

       The most common of these is to dump the data out to an enormous Perl data structure and
       save it into the module itself. The result are enormous multi-megabyte .pm files that chew
       up a lot of memory needlessly.

       Another method is to put the data "file" after the __DATA__ compiler tag and limit
       yourself to access as a filehandle.

       The problem to solve is really quite simple.

	 1. Write the data files to the system at install time.

	 2. Know where you put them at run-time.

       Perl's install system creates an "auto" directory for both every distribution and for
       every module file.

       These are used by a couple of different auto-loading systems to store code fragments
       generated at install time, and various other modules written by the Perl "ancient
       masters".

       But the same mechanism is available to any dist or module to store any sort of data.

   Using Data in your Module
       "File::ShareDir" forms one half of a two part solution.

       Once the files have been installed to the correct directory, you can use "File::ShareDir"
       to find your files again after the installation.

       For the installation half of the solution, see Module::Install and its "install_share"
       directive.

FUNCTIONS
       "File::ShareDir" provides four functions for locating files and directories.

       For greater maintainability, none of these are exported by default and you are expected to
       name the ones you want at use-time, or provide the ':ALL' tag. All of the following are
       equivalent.

	 # Load but don't import, and then call directly
	 use File::ShareDir;
	 $dir = File::ShareDir::dist_dir('My-Dist');

	 # Import a single function
	 use File::ShareDir 'dist_dir';
	 dist_dir('My-Dist');

	 # Import all the functions
	 use File::ShareDir ':ALL';
	 dist_dir('My-Dist');

       All of the functions will check for you that the dir/file actually exists, and that you
       have read permissions, or they will throw an exception.

   dist_dir
	 # Get a distribution's shared files directory
	 my $dir = dist_dir('My-Distribution');

       The "dist_dir" function takes a single parameter of the name of an installed (CPAN or
       otherwise) distribution, and locates the shared data directory created at install time for
       it.

       Returns the directory path as a string, or dies if it cannot be located or is not
       readable.

   module_dir
	 # Get a module's shared files directory
	 my $dir = module_dir('My::Module');

       The "module_dir" function takes a single parameter of the name of an installed (CPAN or
       otherwise) module, and locates the shared data directory created at install time for it.

       In order to find the directory, the module must be loaded when calling this function.

       Returns the directory path as a string, or dies if it cannot be located or is not
       readable.

   dist_file
	 # Find a file in our distribution shared dir
	 my $dir = dist_file('My-Distribution', 'file/name.txt');

       The "dist_file" function takes two params of the distribution name and file name, locates
       the dist dir, and then finds the file within it, verifying that the file actually exists,
       and that it is readable.

       The filename should be a relative path in the format of your local filesystem. It will
       simply added to the directory using File::Spec's "catfile" method.

       Returns the file path as a string, or dies if the file or the dist's directory cannot be
       located, or the file is not readable.

   module_file
	 # Find a file in our module shared dir
	 my $dir = module_file('My::Module', 'file/name.txt');

       The "module_file" function takes two params of the module name and file name. It locates
       the module dir, and then finds the file within it, verifying that the file actually
       exists, and that it is readable.

       In order to find the directory, the module must be loaded when calling this function.

       The filename should be a relative path in the format of your local filesystem. It will
       simply added to the directory using File::Spec's "catfile" method.

       Returns the file path as a string, or dies if the file or the dist's directory cannot be
       located, or the file is not readable.

   class_file
	 # Find a file in our module shared dir, or in our parent class
	 my $dir = class_file('My::Module', 'file/name.txt');

       The "module_file" function takes two params of the module name and file name. It locates
       the module dir, and then finds the file within it, verifying that the file actually
       exists, and that it is readable.

       In order to find the directory, the module must be loaded when calling this function.

       The filename should be a relative path in the format of your local filesystem. It will
       simply added to the directory using File::Spec's "catfile" method.

       If the file is NOT found for that module, "class_file" will scan up the module's @ISA
       tree, looking for the file in all of the parent classes.

       This allows you to, in effect, "subclass" shared files.

       Returns the file path as a string, or dies if the file or the dist's directory cannot be
       located, or the file is not readable.

SUPPORT
       Bugs should always be submitted via the CPAN bug tracker

       <http://rt.cpan.org/NoAuth/ReportBug.html?Queue=File-ShareDir>

       For other issues, contact the maintainer.

AUTHOR
       Adam Kennedy <adamk@cpan.org>

SEE ALSO
       File::HomeDir, Module::Install, Module::Install::Share, File::ShareDir::PAR

COPYRIGHT
       Copyright 2005 - 2011 Adam Kennedy.

       This program is free software; you can redistribute it and/or modify it under the same
       terms as Perl itself.

       The full text of the license can be found in the LICENSE file included with this module.

perl v5.16.3				    2011-02-01				File::ShareDir(3)
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