my( @cpp , @php, @perl );

find ( ... \&test );

print join "\n", @cpp, "\n";

sub test {

push @cpp, $File::Find::name if is_cpp($File::Find::name);

push @perl, $File::Find::name if is_perl($File::Find::name);

push @php, $File::Find::name if $File::Find::name if is_php( $File::Find::name );

...

or

ack --help type

my @perl = qx{ack --perl "$startdir"};

my @php = qx{ack --php "$startdir"};

my @cpp = qx{ack --cpp "$startdir"};