"my $fh" works fine if you only want to work with files you open() yourself, but what if you want to write a function that, based on some test, returns either that or the preexisting STDOUT filehandle?
sub foo {
if (whatever) {
open my $fh, ...;
return $fh;
} else {
return \*STDOUT;
}
}
demeisen=; perl -e 'my $in_fh = (defined $ARGV[0] and $ARGV[0] ne "-") ? do { open my $fh, "<", $ARGV[0] or die "Failed to open $ARGV[0]: $!"; $fh } : \*STDIN; print "Line: ".<$in_fh>;'
HELLO
Line: HELLO
demeisen=; perl -e 'my $in_fh = (defined $ARGV[0] and $ARGV[0] ne "-") ? do { open my $fh, "<", $ARGV[0] or die "Failed to open $ARGV[0]: $!"; $fh } : \*STDIN; print "Line: ".<$in_fh>;' -
HELLO
Line: HELLO
demeisen=; echo 'HI' >tmp/hi
demeisen=; perl -e 'my $in_fh = (defined $ARGV[0] and $ARGV[0] ne "-") ? do { open my $fh, "<", $ARGV[0] or die "Failed to open $ARGV[0]: $!"; $fh } : \*STDIN; print "Line: ".<$in_fh>;' tmp/hi
Line: HI
demeisen=;