## MyModule.pm first

package MyModule;
use strict;

sub isFile {
    my($file, $verbose) = @_;
    print "checking file '$file': " if ($verbose);
    if (! -f $file) {
        print "not found\n" if ($verbose);
        return 0;
    }
    else {
        print "found\n" if ($verbose);
        return 1;
    }
}

sub new {
    my $class = shift;
    my %self = @_;

    return bless \%self, $class . 'OO';
}

package MyModuleOO;
use strict;

sub isFile {
    my($self, $file, $verbose) = @_;

    $verbose = $self->{verbose} unless (defined $verbose);
    MyModule::isFile($file, $verbose);
}

sub verboseOff {
    my($self) = @_;

    $self->{verbose} = 0;
}

1;

## t.pl usage test

use strict;
use MyModule;

if (MyModule::isFile('MyModule.pm', 1)) {
    print "ok\n";
}

my $env = MyModule->new(verbose => 1);

if ($env->isFile('MyModule.pm')) {
    print "ok\n";
}

$env->verboseOff;

if ($env->isFile('MyModule.pm')) {
    print "ok\n";
}