Next steps¶

Default exports

Note that the module in the synopsis doesn't export anything by default. If people load "MyUtils" like this:

   use MyUtils;

Then they haven't imported any functions. You can specify a default set of functions to be exported like this:

   package MyUtils;
   
   use Exporter::Shiny qw( frobnicate );
   
   our @EXPORT = qw( frobnicate );
   
   sub frobnicate { ... }
   
   1;

Or, if you want to be a superstar rock god:

   package MyUtils;
   
   use Exporter::Shiny our @EXPORT = qw( frobnicate );
   
   sub frobnicate { ... }
   
   1;

Tags

You can provide tags for people to use:

   package MyUtils;
   
   use Exporter::Shiny qw( frobnicate red green blue );
   
   our %EXPORT_TAGS = (
      utils   => [qw/ frobnicate /],
      colours => [qw/ red green blue /],
   );
   
   sub frobnicate { ... }
   sub red        { ... }
   sub green      { ... }
   sub blue       { ... }
   
   1;

And people can now import your functions like this:

   use MyUtils ":colours";

Or this:

   use MyUtils "-colours";

Or take advantage of the fact that Perl magically quotes barewords preceded by a hyphen:

   use MyUtils -colours;

Two tags are automatically defined for you: "-default" (which is just the same as @EXPORT) and "-all" (which is the union of @EXPORT and @EXPORT_OK). If you don't like them, then you can override them:

   our %EXPORT_TAGS = (
      default => \@some_other_stuff,
      all     => \@more_stuff,
   );

Generators

Exporting normally just works by copying a sub from your package into your caller's package. But sometimes it's useful instead to generate a custom sub to insert into your caller's package. This is pretty easy to do.

   package MyUtils;
   
   use Exporter::Shiny qw( frobnicate );
   
   sub _generate_frobnicate {
      my ( $me, $name, $args, $globals ) = @_;
      my $caller = $globals->{into};
      
      return sub {
          ...;  # your code here
      };
   }
   
   1;

The parameter $me here is a string containing the package name which is being imported from; $caller is the destination package; $name is the name of the sub (in this case "frobnicate"); and $args is a custom argument for this function. (By convention, $args is normally a hashref.)

   # The hashref { foo => 42 } is $args above.
   #
   use MyUtils "frobnicate" => { foo => 42 };

Avoiding Exporter::Shiny¶

Exporter::Shiny is a tiny shim around Exporter::Tiny. It should mostly do what you want, but you may sometimes prefer to use Exporter::Tiny directly.

The example in the synopsis could have been written as:

   package MyUtils;
   
   use parent "Exporter::Tiny";
   our @EXPORT_OK = qw( frobnicate );
   
   sub frobnicate {
      ...;   # your code here
   }
   
   1;

What Exporter::Shiny does is mostly just to set @EXPORT_OK for you and set up inheritance from the base class (Exporter::Tiny).

Exporter::Shiny also sets $INC{'MyUtils.pm'} for you, which in usually makes little difference, but is useful in some edge cases.