Perl::...y::Each(3pm)

📦
version 1.0.4 · 4 versions
, in debian trixie, ubuntu resolute, ubuntu stonking

💖 Perl::...y::Each(3pm) 💖

okay so bestie, welcome to a page from the User Contributed Perl Documentation manual — yes that's the manual name, we're in the community-contributed corner of the perl docs and it's giving ✨ public service announcement ✨. This one's short, this one's spicy, and this one will save your hash from doing a full-on meltdown. 🫶

🌸 NAME 🌸

Perl::Critic::Policy::Community::Each — the policy that says: do not use each to iterate through a hash. that's it. that's the whole vibe check. 💅

✨ DESCRIPTION ✨

okay so here's the tea, and it's lowkey important so pay attention. 🍓

The each() function relies on an iterator that lives inside the hash (or array) itself. and here's the plot twist: it's the same iterator that keys() and values() use. same one. shared. one iterator, three functions, zero chill. 😭

so what happens if you mess with it mid-iteration?

  • deleting hash elements during iteration? 💀
  • adding hash elements during iteration? 💀💀
  • or just calling keys() or values() on that hash while you're in the middle of it? 💀💀💀

all of those cause undefined behavior, and your code will likely break. no cap. and it gets worse — this can happen even if you just pass the hash to some other function that happens to operate on the hash. sneaky! 🙈

so what's the move instead? use a "foreach" loop iterating through the keys or the values of the hash. that's the main character energy we're looking for. 👑

  while (my ($key, $value) = each %hash) { ... }                # not ok
  foreach my $key (keys %hash) { my $value = $hash{$key}; ... } # ok
  foreach my $i (0..$#array) { my $elem = $array[$i]; ... }     # ok

see how the bottom two are just... calm? peaceful? unbothered? that's the goal. 🧚

🎀 AFFILIATION 🎀

This policy is part of Perl::Critic::Community. it runs with its little community friends. found family fr fr. 🌈

💜 CONFIGURATION 💜

This policy is not configurable except for the standard options. that's right, no knobs, no toggles, no secret settings menu. it just is what it is and honestly? iconic. ✨

🌟 AUTHOR 🌟

Dan Book, "dbook@cpan.org" — thank you for your service, we are obsessed. 🫶

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 🦋

and that's the whole page bestie!! 💖 this came from perl v5.40.1, dated 2025-03-22, under the Perl::...y::Each(3pm) title (which, yes, is the short form of Perl::Critic::Policy::Community::Each — the manpage renderer had to truncate it, we don't make the rules 😭). stay safe out there, and please, for the love of everything, stop each-ing your hashes. mwah 💅🎀🌸

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