B::Showlex(3perl)

💖 B::Showlex — the Perl Programmers Reference Guide bestie edition 💖

okay so you know how you're staring at your Perl code like "where tf do my lexicals even live"?? that's literally what B::Showlex(3perl) is for and she eats every time. she's part of that whole B:: backend universe and bby she will show you the lexicals. no cap.

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✨ NAME ✨

B::Showlex — Show lexical variables used in functions or files 🦋

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✨ SYNOPSIS ✨

perl -MO=Showlex[,-OPTIONS][,SUBROUTINE] foo.pl

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✨ DESCRIPTION ✨

so here's the vibe 💅 — when you hand it a comma-separated list of subroutine names as options, Showlex prints out the lexical variables that get used inside those subroutines. cute.

otherwise? she prints the file-scope lexicals in the file instead. either way you're getting the tea 🍓

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✨ EXAMPLES ✨

🌸 the traditional form

 $ perl -MO=Showlex -e 'my ($i,$j,$k)=(1,"foo")'
 Pad of lexical names for comppadlist has 4 entries
 0: (0x8caea4) undef
 1: (0x9db0fb0) $i
 2: (0x9db0f38) $j
 3: (0x9db0f50) $k
 Pad of lexical values for comppadlist has 5 entries
 0: SPECIAL #1 &PL_sv_undef
 1: NULL (0x9da4234)
 2: NULL (0x9db0f2c)
 3: NULL (0x9db0f44)
 4: NULL (0x9da4264)
 -e syntax OK

🌈 the new-style form

 $ perl -MO=Showlex,-newlex -e 'my ($i,$j,$k)=(1,"foo")'
 main Pad has 4 entries
 0: (0x8caea4) undef
 1: (0xa0c4fb8) "$i" = NULL (0xa0b8234)
 2: (0xa0c4f40) "$j" = NULL (0xa0c4f34)
 3: (0xa0c4f58) "$k" = NULL (0xa0c4f4c)
 -e syntax OK

🧚 new form, no specials, outside the O framework

 $ perl -MB::Showlex -e \
    'my ($i,$j,$k)=(1,"foo"); B::Showlex::compile(-newlex,-nosp)->()'
 main Pad has 4 entries
 1: (0x998ffb0) "$i" = IV (0x9983234) 1
 2: (0x998ff68) "$j" = PV (0x998ff5c) "foo"
 3: (0x998ff80) "$k" = NULL (0x998ff74)

lowkey important: this third example actually shows you the values of the lexicals, whereas the other examples did not (because those are compile-time only). iykyk 👑

💅 OPTIONS

• -newlex — this one gives you a way more readable "name => value" format, and you can peep her in the second example up above ✨
• -nosp — this one kills the reporting of SPECIALs, like 0: SPECIAL #1 &PL_sv_undef from the example above. real talk, SPECIAL reporting can sometimes just completely overwhelm your declared lexicals 😭

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✨ SEE ALSO ✨

B::Showlex can also be used outside of the O framework, just like in the third example bestie. and if you want the full explanation of the reasons and the whole lore? see B::Concise 💜

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✨ TODO ✨

ngl some of the stuff she reports — hex addresses and whatnot — is not particularly valuable 🙈 other info would be way more useful for the typical programmer, like line-numbers, pad-slot reuses, etc.. and given all that, -newlex is honestly not a particularly good flag-name. we said it. 💀

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✨ AUTHOR ✨

Malcolm Beattie, "mbeattie@sable.ox.ac.uk" 🎀

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okay and one last thing bestie, so you have the receipts: this was perl v5.44.0, dated 2026-10-17, and it's the B::Showlex(3perl) page from the Perl Programmers Reference Guide. slay 🫶✨👑