sub show {
    my @data = @_;
    for (@data) {
        s/(\266|\267)/sprintf"%%%02X",ord $1/egm;
        s/ /chr(0267)/egm;
        s/\t/ -> /gm;
        s/\n/chr(0266)."\n"/egm;
    }
  return wantarray ? @data : join'',@data;
}

sub hide {
    my @data = @_;
    for (@data) {
        s/ -> /\t/gm;
        s/\266//gm;
        s/\267/ /gm;
        s/%([0-9a-f][0-9a-f])/chr hex $1/eigm;
    }
  return wantarray ? @data : join'',@data;
}

@data = (<DATA>)[0..7];

print "Original data, including specials\n\n";
print @data;

print "\n\nShow invisible chars in data\n\n";
print show(@data);

print "\n\nHide and show data - should not change\n\n";
print hide(show(@data));

__DATA__
	tab
    4 spaces, trailing tab	
	    tab and 4 spaces
		
····4·spaces,·trailing·tab -> ¶
 -> ····tab·and·4·spaces¶
 ->  -> ¶
¶