Provided by: libbest-perl_0.15-2_all bug

NAME

       Best - Load modules with fallback

SYNOPSIS

           # Load the best available YAML module with default imports
           use Best qw/YAML::Syck YAML/;
           use Best [ qw/YAML::Syck YAML/ ];   # also works

           # Load a YAML module and import some symbols
           use Best [ [ qw/YAML::Syck YAML/ ], qw/DumpFile LoadFile/ ];

           # And fancier stuff...

           # Load a new enough YAML module
           use Best qw/YAML 0.58 YAML::Syck/;
           use Best [ qw/YAML 0.58 YAML::Syck/ ];
           use Best [ [ 'YAML' => { version => '0.58' },
                        'YAML::Syck' ] ];

           # Don't load too-new YAML module and import DumpFile
           use Best [ [ 'YAML' => { ok => sub { YAML->VERSION <= 0.23 } },
                        'YAML::Syck', ],
                      qw/DumpFile/ ];

           # Use the best Carp module w/ different parameter lists
           use Best [ [ 'Carp::Clan' => { args => [] },
                        'Carp' ],
                      qw/croak confess carp cluck/ ];

           # Choose alternate implementations
           use Best [ [ 'My::Memoize' => { if => sub { $] <= 5.006 } },
                        'Memoize' ],
                      qw/memoize/ ];

           # Load a CGI module but import nothing
           use Best [ [ qw/CGI::Simple CGI/ ], [] ];      # akin to 'use CGI ()'

DESCRIPTION

       Often there are several possible providers of some functionality your program needs, but
       you don't know which is available at the run site. For example, one of the modules may be
       implemented with XS, or not in the core Perl distribution and thus not necessarily
       installed.

       Best attempts to load modules from a list, stopping at the first successful load and
       failing only if no alternative was found.

FUNCTIONS

       Most of the functionality Best provides is on the "use" line; there is only one callable
       functions as such (see "which" below)

       If the arguments are either a simple list or a reference to a simple list, the elements
       are taken to be module names and are loaded in order with their default import function
       called. Any exported symbols are installed in the caller package.

         use Best qw/A Simple List/;
         use Best [ qw/A Simple List/ ];

   IMPORT LISTS
       If the arguments are a listref with a listref as its first element, this interior list is
       treated as the specification of modules to attempt loading, in order; the rest of the
       arguments are treated as options to pass on to the loaded module's import function.

         use Best [ [ qw/A Simple List/ ],
                    qw/Argument list goes here/ ];
         use Best [ [ qw/A Simple List/ ],
                    [ qw/Argument list goes here/ ] ];

       To specify a null import ("use Some::Module ()"), pass a zero-element listref as the
       argument list. In the pathological case where you really want to load a module and pass it
       "[]" as an argument, specify "[ [] ]" as the argument list to Best.

         # use Module ();
         use Best [ [ 'Module' ], [] ];

         # use Module ( [] );
         use Best [ [ 'Module' ], [[]] ];

       To customize the import list for a module, use the "args" parameter in a hash reference
       following the module's name.

         # use Carp::Clan;
         # use Carp qw/carp croak confess cluck/;
         use Best [ [ 'Carp::Clan' => { args => [] },
                      'Carp' ],
                    qw/carp croak confess cluck/ ];

   MINIMUM VERSIONS
       You can specify a minimum version for a module by following the module name with something
       that looks like a number or by a hash reference with a "version" key.

         use Best [ [ YAML => '0.58',
                      'YAML::Syck' ] ];

         use Best [ [ YAML => { version => '0.58' },
                      'YAML::Syck' ] ];

   PRE-VALIDATION
         use Best Module => { if => CODEREF };

       You may prevent Best from attempting to load a module by providing a function as a
       parameter to "if". The module will only be loaded if your function returns a true value.

   POST-VALIDATION
         use Best Module => { ok => CODEREF };

       You may prevent Best from settling on a successfully loaded module by providing a function
       as a parameter to "ok". Best will follow all of its normal rules to attempt to load your
       module but can be told to continue retrying if your function returns false.

   ARBITRARY CODE
       A code reference may be substituted for module names. It will be called instead of
       attempting to load a module. You may do anything you wish in this code. It will be skipped
       if your code throws an exception or returns false.

         use Best [ sub {
                        # Decline
                        return;
                    },
                    sub {
                        # Oops!
                        die 'Some error';
                    },
                    'Bad::Module',
                    sub {
                        # Ok!
                        return 1;
                    }, ];

       which
           In some cases--for example, class methods in OO modules--you want to know which module
           Best has successfully loaded. Call "Best->which" with the first in your list of module
           alternatives; the return value is a string containing the name of the loaded module.

DEPLOYMENT ISSUES

       If you want to use Best because you aren't sure your target machine has some modules
       installed, you may wonder what might warrant the assumption that "Best.pm" would be
       available, since it isn't a core module itself.

       One solution is to use Inline::Module to inline "Best.pm" in your source code. If you
       don't know this module, check it out -- after you learn what it does, you may decide you
       don't need Best at all! (If your fallback list includes XS modules, though, you may need
       to stick with us.)

       "Best.pm" is pure Perl and a single module with a convenient license, so you can also just
       drop it in your project's "lib" directory.

SEE ALSO

       Module::Load
       UNIVERSAL::require
       Inline::Module

AUTHORS

       Gaal Yahas, "<gaal at forum2.org>"

       Joshua ben Jore, "<jjore at cpan.org>" has made some significant contributions.

DIAGNOSTICS

       What modules shall I load?
           "Best" wasn't given a list of modules to load.

       No viable module found: %s
           None of the module alternatives loaded.

       Something's wrong!
           An assertion failed. This means that either there is a bug in the data you fed to Best
           or a bug in Best.

       The code is scattered with assertions and debugging output that can be enabled by putting
       a true value in the environment variables "TRACE_BEST" and "DEBUG_BEST".

       Enabling "TRACE_BEST" also enables the debugging code.

BUGS

       Please report any bugs or feature requests to "bug-template-patch at rt.cpan.org", or
       through the web interface at <http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Best>.  I
       will be notified, and then you'll automatically be notified of progress on your bug as I
       make changes.

SUPPORT

       You can find documentation for this module with the perldoc command.

           perldoc Best

       You can also contact the maintainer at the address above or look for information at:

       ·   AnnoCPAN: Annotated CPAN documentation

           <http://annocpan.org/dist/Best/>

       ·   CPAN Ratings

           <http://cpanratings.perl.org/d/Best/>

       ·   RT: CPAN's request tracker

           <http://rt.cpan.org/NoAuth/Bugs.html?Dist=Best>

       ·   Search CPAN

           <http://search.cpan.org/dist/Best/>

       ·   Source repository

           <https://github.com/gaal/best>

COPYRIGHT (The "MIT (X11)" License)

       Copyright (C) 2006-2012 Gaal Yahas

       This program is distributed under the MIT (X11) License:
       <http://www.opensource.org/licenses/mit-license.php>

       Permission is hereby granted, free of charge, to any person obtaining a copy of this
       software and associated documentation files (the "Software"), to deal in the Software
       without restriction, including without limitation the rights to use, copy, modify, merge,
       publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
       to whom the Software is furnished to do so, subject to the following conditions:

       The above copyright notice and this permission notice shall be included in all copies or
       substantial portions of the Software.

       THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
       PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
       FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
       OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
       DEALINGS IN THE SOFTWARE.