Modifying exports in before_export.

gistfile1.pl

sub before_import {
    my ( $dest, $spec ) = @_;
       
    if ( $spec->config->{someoption} ) {
        $spec->exports->{foo} = [
            Exporter::Declare::Export::Sub->new(
                sub { ... }, 
                exported_by => __PACKAGE__,
            ), 
            {},
            [] 
        ]; 
    }  
}