Why You Should Be Using Perl’s Built‑In ‘say’ Function (and When to Avoid It)

The Problem: Newlines the Hard Way

When writing Perl scripts, you almost always need to output text that ends with a newline. The classic pattern is:

print "Hello, world!\n";

If you forget the "\n", the output can be garbled or the terminal can behave oddly. Mixing print and say in the same file also creates a visual inconsistency that can confuse readers of your code.

Thesis: ‘say’ Simplifies Output and Reduces Bugs

The core say function, introduced in Perl 5.10, automatically appends a newline to the string you pass, so you no longer have to remember to add "\n" manually. It’s a small change that makes scripts cleaner, easier to read, and less error‑prone.

How to Enable and Use ‘say’

• In Perl 5.10 and newer, say is available by default. For older codebases, enable it with use feature qw(say); or use 5.10;.
• It behaves like print but always appends a newline.
• Example:

  use 5.10;
  
  say "First line";
  print "Second line without a newline";
  say "Third line";
  

  The output will be:

  First line
  Second line without a newlineThird line
  

Concrete Example: Listing Files with ‘say’

Below is a minimal script that lists all files in a directory. Notice how say removes the need for explicit newlines.

use 5.10;
use strict;
use warnings;

my $dir = ".";
opendir(my $dh, $dir) or die "Cannot open $dir: $!";
while (my $file = readdir $dh) {
    next if $file =~ /^\./; # skip hidden files
    say $file;               # automatic newline
}
closedir $dh;

Running this script will print each filename on its own line, exactly as you’d expect.

Trade‑Offs and Limitations

• No Custom Separator: say always uses a newline. If you need a different separator (e.g., a comma for CSV output), you must fall back to print and set $/, $OUTPUT_AUTOFLUSH, or use join.
• Version Compatibility: say is not available in Perl 5.8 or older. Code that must run on those versions should either avoid say or provide a compatibility shim.
• Semantics with print vs say: Mixing the two can lead to confusing output if you forget that say adds a newline automatically.

Practical Checklist

1. Run perl -v to confirm your interpreter is ≥5.10.
2. Add use 5.10; at the top of your scripts.
3. Replace any print "…\n"; with say "…";.
4. For custom separators, keep print and explicitly set $/ or use join.
5. Run your script and verify that each output line ends with a newline by piping to od -c or inspecting the terminal.

Conclusion

Adopting say in modern Perl codebases is a quick win: it cleans up your print statements, eliminates a common source of bugs, and makes your intent clearer. Just remember its limitations—especially the lack of a custom separator and the version requirement—so you can decide whether it fits your project’s constraints.