my $stuff;
for(scalar something()) {
    # ...
    $stuff = $_;
}

##</code><code>##

my $stuff = something();
for($stuff) {
    # ...
}

##</code><code>##

my $stuff;
for(something()) {
    # ...
    $stuff = $_;
}

##</code><code>##

my ($stuff) = something();
for($stuff) {
    # ...
}