#!/usr/bin/perl -w

use open qw/:std
            :encoding(iso-8859-1)/;       # default I/O encoding

my $s = "A \N{WHITE SMILING FACE} for you\n";

open (FILE, '> fpo');                     # in the actual code, may open one of several things, or assign STDOUT to FILE
binmode(FILE, ':encoding(utf8)') if 1;    # override the default encoding under certain conditions

warn "About to print";                    # primitive trace statement
print FILE "$s";

##</code><code>##

About to print at ./fp line 11.
"\x{263a}" does not map to iso-8859-1.