use Carp;
use Storable qw(dclone);
use Hook::LexWrap;
use Devel::Symdump;

our $Monitoring;

sub monitor_arg {
    my %param = @_;
    my ($matching, $in_package, $with) = 
        map {$param{$_} or croak "need $_"} 
        	qw(matching in_package with);
    croak "called in void context" unless defined wantarray;
    my @wrappers;
    foreach my $subroutine (Devel::Symdump->functions(@$in_package)) {
        my ($original, @current);
        push @wrappers, wrap $subroutine,
            pre => sub {
                return if $Monitoring;
                local $Monitoring = 1;
                @current = grep { $matching->($_) } @_;
                $original = dclone(\@current);
            },
            post => sub {
                return if $Monitoring;
                local $Monitoring = 1;
                foreach my $current (@current) {
                    my $original = shift @$original;
                    $with->($original, $current, $subroutine);
                }
            };      
    };
    return \@wrappers;
};