# LogOnce.pm

package LogOnce;

use warnings;
use strict;

our @ISA = qw(Exporter);
use Exporter;

our @EXPORT    =   ();
our @EXPORT_OK = qw(log1);

my %once;


sub log1 {

    my $signature = join '|', caller;
    return if exists $once{$signature};

    return $once{$signature} = print __PACKAGE__, ": @_ \n";

    }


1;


# LogOnce.t

use warnings;
use strict;

use LogOnce qw(log1);


MAIN: {

log1('this should print', __FILE__, __LINE__);

t_log1_1('this should print');
t_log1_1('this should NOT print');

log1('this should print', __FILE__, __LINE__);

t_log1_2('this should print');
t_log1_2('this should NOT print');

log1('this should print', __FILE__, __LINE__);

}


sub t_log1_1 {

    log1('called at', __FILE__, __LINE__, ':', @_);
    log1('called at', __FILE__, __LINE__, ':', @_);

    }


sub t_log1_2 {

    t_log1_1('should NOT print', __FILE__, __LINE__);

    log1('called at', __FILE__, __LINE__, ':', @_);
    log1('called at', __FILE__, __LINE__, ':', @_);

    t_log1_1('should NOT print', __FILE__, __LINE__);

    }