sub openFileForAppending(*$)
{
	my $handle = qualify_to_ref(shift, caller);;
	my $name   = shift;

	open($handle, '>> ' . $name) or return;
	attemptFlock($handle, LOCK_EX);

	return $handle;
}

...

sub openFileForWriting(*$)
{
	my $handle = qualify_to_ref(shift, caller);
	my $name   = shift;

	# If a file with that name exists, we'll open it for reading and
	# writing to prevent clobbering it prematurely before flock()ing it.
	# If we can successfully open it, then we'll try to flock() it, *then*
	# we can safely clobber it:
	if (-e $name)
	{
		open($handle, '+< ' . $name) or return;
		attemptFlock($handle, LOCK_EX);
		seek($handle, 0, 0);
		truncate($handle, 0);
	}
	else
	{
		open($handle, '> ' . $name) or return;
		attemptFlock($handle, LOCK_EX);
	}

	return $handle;
}

##</code><code>##

openFileForWriting(TEST, 'test.txt');
print TEST "A test.\n";
close TEST;

##</code><code>##

openFileForWriting(TEST, 'test.txt');
print TEST test();
close TEST;

sub test
{
	return "Another test.\n"
}