10.8. 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 $line;
} Reading an entire file into memory makes sense only when the file is unstable in some way, or is being updated asynchronously and you need a "snapshot", or if your planned text processing is likely to cross line boundaries:
sub get_C_code {
my ($filename) = @_;
Because C comments can span multiple lines, it's necessary to load the entire file into memory at once so the pattern can detect such cases. |