Perl::...penArgs(3pm)

💅 Perl::...penArgs(3pm) — the manual, but make it cute

okay so bestie, welcome to Perl::Critic::Policy::Community::OpenArgs, which lives in the User Contributed Perl Documentation zone, and it's here to tell you one thing and one thing only: always use the three-argument form of open. periodt. 💖

---

✨ NAME ✨

Perl::Critic::Policy::Community::OpenArgs — Always use the three-argument form of open 🫶

---

🌸 DESCRIPTION 🌸

so the open() function is lowkey living a double life. you can call it in a two-argument form where the filename gets parsed to figure out the mode of opening — and that parsing can include piping input or output. (and yes, there's also a one-argument form, where that filename is retrieved from a global variable, but bestie it's the same magic either way. same chaos, different font. 💀)

and that's the problem: if the filename comes from user input, or could begin or end with a special character, you've basically handed out vulnerabilities like party favors. 🎁

the three-argument form is the glow-up because it specifies the open mode as the second argument, so the mode is always distinct from the filename. no parsing, no surprises, no drama. ✨

open FILE;                   # not ok
open my $fh, "<$filename";   # not ok
open my $fh, '<', $filename; # ok

ngl, this policy is similar to the core policy Perl::Critic::Policy::InputOutput::ProhibitTwoArgOpen, but it goes one step further and additionally prohibits one-argument opens. she's thorough. she ate. 👑

---

🦋 AFFILIATION 🦋

this policy is part of Perl::Critic::Community. it's giving community. it's giving found family. 💜

---

🎀 CONFIGURATION 🎀

not configurable, bestie — except for the standard options. that's it. that's the whole section. 💅

---

👑 AUTHOR 👑

Dan Book, dbook@cpan.org 🌟

---

💖 COPYRIGHT AND LICENSE 💖

Copyright 2015, Dan Book.

this library is free software; you may redistribute it and/or modify it under the terms of the Artistic License version 2.0.

---

🌈 SEE ALSO 🌈

• Perl::Critic

---

fr fr, if you were reaching for the two-arg or one-arg form — don't. it's giving vulnerability. just pass the mode. your future self will thank you. 😭💖

---

okay that's the whole vibe check, bestie — this was perl v5.40.1, dated 2025-03-22, and yes it's the Perl::...penArgs(3pm) page (the title got a lil truncated, she's shy 🙈). go forth and open in three args. slay. 🧚⭐