NAME

       Return::Type - specify a return type for a function (optionally with coercion)

SYNOPSIS

          use Return::Type;
          use Types::Standard qw(Int);

          sub first_item :ReturnType(Int) {
             return $_[0];
          }

          my $answer = first_item(42, 43, 44);     # returns 42
          my $pie    = first_item(3.141592);       # throws an error!

DESCRIPTION

       Return::Type allows you to specify a return type for your subs. Type constraints from any
       Type::Tiny, MooseX::Types or MouseX::Types type library are supported.

       The simple syntax for specifying a type constraint is shown in the "SYNOPSIS". If the
       attribute is passed a single type constraint as shown, this will be applied to the return
       value if called in scalar context, and to each item in the returned list if called in list
       context. (If the sub is called in void context, type constraints are simply ignored.)

       It is possible to specify different type constraints for scalar and list context:

          sub foo :ReturnType(scalar => Int, list => HashRef[Num]) {
             if (wantarray) {
                return (pie => 3.141592);
             }
             else {
                return 42;
             }
          }

       Note that because type constraint libraries are really aimed at validating scalars, the
       type constraint for the list is specified as a hashref of numbers and not a hash of
       numbers! For the purposes of validation against the type constraint, we slurp the returned
       list into a temporary arrayref or hashref.

       For type constraints with coercions, you can also pass the option "coerce => 1":

          use Return::Type;
          use Types::Standard qw( Int Num );

          # Define a subtype of "Int" at compile time, which can
          # coerce from "Num" by rounding to nearest integer.
          use constant Rounded => Int->plus_coercions(Num, sub { int($_) });

          sub first_item :ReturnType(scalar => Rounded, coerce => 1) {
             return $_[0];
          }

          my $answer = first_item(42, 43, 44);     # returns 42
          my $pie    = first_item(3.141592);       # returns 3

       The options "coerce_scalar" and "coerce_list" are also available if you wish to enable
       coercion only in particular contexts.

   Power-user Inferface
       Rather than using the ":ReturnType" attribute, it's possible to wrap a coderef like this:

          my $wrapped = Return::Type->wrap_sub($orig, %options);

       The accepted options are "scalar", "list", "coerce", "coerce_list", and "coerce_scalar",
       as per the attribute-based interface.

       There is an additional option "scope_upper" which will load and use Scope::Upper so that
       things like "caller" used within the wrapped sub are unaware of being wrapped. This
       behaviour was the default prior to Return::Type 0.004, but is now optional and disabled by
       default.

BUGS

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

SUPPORT

       IRC: support is available through in the #moops channel on irc.perl.org
       <http://www.irc.perl.org/channels.html>.

SEE ALSO

       Attribute::Contract, Sub::Filter, Sub::Contract.

AUTHOR

       Toby Inkster <tobyink@cpan.org>.

COPYRIGHT AND LICENCE

       This software is copyright (c) 2013-2014 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.