# let us inject input into STDIN

my $injector = inject_input(*STDIN);

# the resulting injector takes a string to inject

$injector->("1234\n");       # inject 1234
print "r: ", scalar <STDIN>; # read 1234 back in

# now we can inject 5678, a, and b
# we can read them back in via a loop

$injector->("5678\n");       # inject 5678
$injector->("a\n", "b\n");   # inject a and b

while (<>) {
    print "R: $_";
}

# after the read loop reaches the EOF, we
# can still inject more input and read it

$injector->("we're outta here\n");
print "r: ", <>;

# when we are done, we call the injector with
# no arguments; this will close down the injection
# apparatus, restore STDIN to its pre-injection
# condition, and return a copy of what was injected
# for flight-recording purposes 

print "\n\nwe injected:\n\n", $injector->();

# now STDIN is restored

print "\n\nEnter text by hand:\n";
while (<>) {
    print "You entered: $_";
}

# actual output follows:

__END__
r: 1234
R: 5678
R: a
R: b
r: we're outta here


we injected:

1234
5678
a
b
we're outta here


Enter text by hand:
blah
You entered: blah
blah
You entered: blah
blah
You entered: blah