NAME
    LV - LV ♥ lvalue

SYNOPSIS
       use LV qw( lvalue get set );
   
       my $xxx;
       sub xxx :lvalue {
          lvalue
             get { $xxx }
             set { $xxx = $_[0] }
       }
   
       xxx() = 42;
       say xxx();    # says 42

DESCRIPTION
    This module makes lvalue subroutines easy and practical to use. It's
    inspired by the lvalue module which is sadly problematic because of the
    existence of another module on CPAN called Lvalue. (They can get confused
    on file-systems that have case-insensitive file names.)

    LV comes with three different implementations, based on Variable::Magic,
    Sentinel and `tie`; it will choose and use the best available one. You can
    force LV to pick a particular implementation using:

       $ENV{PERL_LV_IMPLEMENTATION} = 'Magic'; # or 'Sentinel' or 'Tie'

    The tie implementation is the slowest, but will work on Perl 5.6 with only
    core modules.

  Functions
    `lvalue(%args)`
        Creates the magic lvalue. This must be the last expression evaluated
        by the lvalue sub (and thus will be returned by the sub) but also must
        not be returned using an explicit `return` keyword (which would break
        its lvaluedness).

        As a matter of style, you may like to omit the optional semicolon
        after calling this function, which will act as a reminder that no
        statement should follow this one.

        The arguments are `get` and `set`, which each take a coderef:

           sub xxx :lvalue {
              lvalue(
                 get => sub { $xxx },
                 set => sub { $xxx = $_[0] },
              ); # semicolon
           }

        Note that the `set` coderef gets passed the rvalue part as $_[0].

    `get { BLOCK }`, `set { BLOCK }`
        Convenience functions for defining `get` and `set` arguments for
        `lvalue`:

           sub xxx :lvalue {
              lvalue
                 get { $xxx }
                 set { $xxx = $_[0] }
           }

        As well as populating %args for `lvalue`, these functions also use
        Sub::Name (if it's installed) to ensure that the anonymous coderefs
        have sensible names for the purposes of stack traces, etc.

        These functions are not exported by default.

    `implementation()`
        Can be used to determine the current backend.

        Cannot be exported.

BUGS
    Please report any bugs to <http://rt.cpan.org/Dist/Display.html?Queue=LV>.

SEE ALSO
    lvalue, Sentinel.

AUTHOR
    Toby Inkster <tobyink@cpan.org>.

COPYRIGHT AND LICENCE
    This software is copyright (c) 2013 by Toby Inkster.

    This is free software; you can redistribute it and/or modify it under the
    same terms as the Perl 5 programming language system itself.

DISCLAIMER OF WARRANTIES
    THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED
    WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
    MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.

