I was starting to write a constants module (and hating it) when the following funkiness sprang to mind.
This seems nicer to me than the standard way because I don't have to keep track of them in two places (in the constants pragma *and* the export list).
You can also do something like the second one if you really want to go all out.
Update: This only works with 5.8.0. 5.6.1 + earlier don't support creating multiple constants with a single use statement:( 
package foo;
use base qw( Exporter );

my %constants;
use constant +{
    %constants = (
        AAA => 1,
        BBB => 2,
        CCC => 3,
        DDD => 4,
    )
};

our @EXPORT = keys %constants;

1;


package foo2;
use base qw( Exporter );

my %all;
my %foo;
my %bar;
use constant +{
    %all = (
        %foo = (
            AAA => 1,
            BBB => 2,
        ),
        %bar = (
            CCC => 3,
            DDD => 4,
        ),
    )    
};

our @EXPORT_OK = keys %all;
our %EXPORT_TAGS = (
    all => [ keys %all ],
    foo => [ keys %foo ],
    bar => [ keys %bar ],
);

1;

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In reply to Creating constants modules by Felonious

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