Under mod_perl, CORE::print( ) (using either STDOUT as a filehandle argument or no filehandle at all) will redirect output to Apache::print( ), since the STDOUT file handle is tied to Apache. That is, these two are functionally equivalent:

print "Hello";
$r->print("Hello");

Apache::print( ) will return immediately without printing anything if $r->connection->aborted returns true. This happens if the connection has been aborted by the client (e.g., by pressing the Stop button).

There is also an optimization built into Apache::print( ): if any of the arguments to this function are scalar references to strings, they are automatically dereferenced. This avoids needless copying of large strings when passing them to subroutines. For example, the following code will print the actual value of $long_string:

my $long_string = "A" x 10000000;
$r->print(\$long_string);

To print the reference value itself, use a double reference:

$r->print(\\$long_string);

When Apache::print( )sees that the passed value is a reference, it dereferences it once and prints the real reference value:

SCALAR(0x8576e0c)