Perl::...tStdin(3pm)

🎀 NAME 🎀

Okay bestie, this is Perl::...tStdin(3pm) — the manual page for Perl::Critic::Policy::InputOutput::ProhibitExplicitStdin. The whole vibe? Use <> or <ARGV> or a prompting module instead of <STDIN>. Periodt. 💅

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🌸 AFFILIATION 🌸

This Policy is part of the core Perl::Critic distribution. Yup, it ships with the main character energy. ✨

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🦋 DESCRIPTION 🦋

Okay so here's the lore, bestie: Perl has a useful magic filehandle called *ARGV that checks the command line and if there are any arguments, opens and reads those as files. If there are no arguments, *ARGV behaves like *STDIN instead. That's the plot twist. 🫶

This behavior is almost always what you want if you want to create a program that reads from STDIN. This is often written in one of the following two equivalent forms:

  while (<ARGV>) {
    # ... do something with each input line ...
  }
  # or, equivalently:
  while (<>) {
    # ... do something with each input line ...
  }

If you want to prompt for user input, try special purpose modules like IO::Prompt. It's giving "there's a module for that" energy. 🎀

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🎀 CONFIGURATION 🎀

No extra knobs, no secret switches, no little config arc. This Policy is not configurable except for the standard options. That's the whole story. 💅

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💀 CAVEATS 💀

Okay, important caveat time — pay attention, bestie. Due to a bug in the current version of PPI (v1.119_03) and earlier, the readline operator is often misinterpreted as less-than and greater-than operators after a comma. So this policy misses important cases like:

my $content = join '', <STDIN>;

because it interprets that line as the nonsensical statement:

my $content = join '', < STDIN >;

When that PPI bug is fixed, this policy should start catching those violations automatically. So like, it's not you, it's the parser. 😭

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👑 CREDITS 👑

Initial development of this policy was supported by a grant from the Perl Foundation. Shoutout to them, no cap. 🫶

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🫶 AUTHOR 🫶

Chris Dolan <cdolan@cpan.org> — iconic behavior, honestly. 💖

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🌈 COPYRIGHT 🌈

Copyright (c) 2007-2023 Chris Dolan

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself. The full text of this license can be found in the LICENSE file included with this module

Mwah 💋 — this page came from perl v5.42.0, dated 2024-10-23. Bye bestie! 🎀✨