Line-Based Input

Reading in an entire file in a single <> operation is colloquially known as "slurping". But the considerations of memory allocation discussed in the previous section mean that slurping the contents of a file and then manipulating those contents monolithically, like so:

# Slurp the entire file (see the next guideline)...
my $text = do { local $/; <> };

# Wash its mouth out...
$text =~ s/$EXPLETIVE/[DELETED]/gxms;

# Print it all back out...
print $text;

is generally slower, less robust, and less scalable than processing the contents a line at a time:

while (my $line = <>) {
    $line =~ s/$expletive/[DELETED]/gxms;
    print $line;}

Reading an entire file into memory makes sense only when the file is unstable in some way, or is being updated asynchronously and you need a "snapshot", or if your planned text processing is likely to cross line boundaries: