The whole point here is to use
$tee->format_write() instead of write. Then you don't have to fool around with
$^ et al. (it all happens automagically). A better way for me to have shown this might have been with more calls to
$tee->format_write(), as in the following modified version of what I posted earlier.
use strict;
use warnings;
use IO::Tee;
my %hash = map { ("key$_", "val$_") } ( 1 .. 5 );
my $key;
format TEE_TOP =
==== Top of Output ====
.
format TEE =
@<<<<< @<<<<<
$key, $hash{$key}
.
# with lexical file handle; can also use bareword handle
open my $outfile, '>', 'junk.out' or die "error opening junk.out: ($!
+)";
my $tee = IO::Tee->new( \*STDOUT, $outfile );
# see docs for IO::Tee and IO::Handle for explanation of these methods
# and others available for proper format use/control
$tee->format_top_name( q/main::TEE_TOP/ );
for $key ( sort keys %hash ) {
$tee->format_write( q/main::TEE/ );
}
from the shell:
-> ./tst-tee-write
==== Top of Output ====
key1 val1
key2 val2
key3 val3
key4 val4
key5 val5
-> cat junk.out
==== Top of Output ====
key1 val1
key2 val2
key3 val3
key4 val4
key5 val5