NAME

       Dispatch::Class - dispatch on the type (class) of an argument

SYNOPSIS

         use Dispatch::Class qw(
           class_case
           dispatch
         );

         # analyze the class of an object
         my $analyze = class_case(
           'Some::Class'  => 1,
           'Other::Class' => 2,
           'UNIVERSAL'    => "???",
         );
         my $foo = $analyze->(Other::Class->new);  # 2
         my $bar = $analyze->(IO::Handle->new);    # "???"
         my $baz = $analyze->(["not an object"]);  # undef

         # build a dispatcher
         my $dispatch = dispatch(
           'Dog::Tiny' => sub { ... },  # handle objects of the class Dog::Tiny
           'Dog'       => sub { ... },
           'Mammal'    => sub { ... },
           'Tree'      => sub { ... },

           'ARRAY'     => sub { ... },  # handle array refs

           ':str'      => sub { ... },  # handle non-reference strings

           '*'         => sub { ... },  # handle any value
         );

         # call the appropriate handler, passing $obj as an argument
         my $result = $dispatch->($obj);

DESCRIPTION

       This module offers a (mostly) simple way to check the class of an object and handle
       specific cases specially.

   Functions
       The following functions are available and can be imported on request:

       "class_case"
           "class_case" takes a list of "KEY, VALUE" pairs and returns a code reference that
           (when called on an object) will analyze the object's class according to the rules
           described below and return the corresponding VALUE of the first matching KEY.

           Example:

             my $subref = class_case(
               KEY1 => VALUE1,
               KEY2 => VALUE2,
               ...
             );
             my $value = $subref->($some_object);

           This will check the class of $some_object against "KEY1", "KEY2", ... in order and
           return the corresponding "VALUEn" of the first match. If no key matches, an empty
           list/undef is returned in list/scalar context, respectively.

           The following things can be used as keys:

           "*" This will match any value. No actual check is performed.

           ":str"
               This special key will match any non-reference.

           "SCALAR", "ARRAY", "HASH", ...
               These values match references of the specified type even if they aren't objects
               (i.e. not "bless"ed). That is, for unblessed references the string returned by
               "ref" is compared with "eq".

           CLASS
               Any other string is interpreted as a class name and matches if the input value is
               an object for which "$obj->isa($CLASS)" is true. To match any kind of object
               (blessed value), use the key 'UNIVERSAL'.

               Starting with Perl 5.10.0 Perl supports checking for roles with "DOES", so
               "Dispatch::Class" actually uses "$obj->DOES($CLASS)" instead of "isa".  This still
               returns true for normal base classes but it also accepts roles that have been
               composed into the object's class.

       "dispatch"
           This works like "class_case" above, but the VALUEs must be code references and get
           invoked automatically:

             sub dispatch {
               my $analyze = class_case @_;
               sub {
                 my ($obj) = @_;
                 my $handler = $analyze->($obj) or return;
                 $handler->($obj)
               }
             }

           That is, the matching object is passed on to the matched VALUEs and the return value
           of the inner sub is whatever the handler returns (or the empty list/undef if no KEY
           matches).

       This module uses "Exporter::Tiny", so you can rename the imported functions at "use" time.

SEE ALSO

       Exporter::Tiny

AUTHOR

       Lukas Mai, "<l.mai at web.de>"

COPYRIGHT & LICENSE

       Copyright 2013, 2014 Lukas Mai.

       This program is free software; you can redistribute it and/or modify it under the terms of
       either: the GNU General Public License as published by the Free Software Foundation; or
       the Artistic License.

       See http://dev.perl.org/licenses/ for more information.