B::Showlex(3pm)

okay bestie, welcome to the B::Showlex(3pm) page from the Perl Programmers Reference Guide ✨ this is the one about showing lexical variables used in functions or files, and we’re gonna read it together like a group chat. no cap.

💖 NAME 💖

B::Showlex — show lexical variables used in functions or files.

📜 SYNOPSIS 📜

the whole invocation vibe is:

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

🌸 DESCRIPTION 🌸

so here’s the tea: when you give it a comma-separated list of subroutine names as options, Showlex prints the lexical variables used in those subroutines. Otherwise? It prints the file-scope lexicals in the file. that’s the whole plot 💅

🦋 EXAMPLES 🦋

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

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 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)

Note that this example shows the values of the lexicals, whereas the other examples did not (as they’re compile-time only). iconic behavior, honestly 🫶

🎀 OPTIONS 🎀

• -newlex — this one produces a more readable "name => value" format, and it’s the one shown in the second example above. cute and useful, we love.
• -nosp — this one eliminates reporting of SPECIALs, like 0: SPECIAL #1 &PL_sv_undef up above. Reporting of SPECIALs can sometimes overwhelm your declared lexicals, so this is the “okay bestie, breathe” option 💀

🔥 SEE ALSO 🔥

B::Showlex can also be used outside of the O framework, as in the third example. See B::Concise for a fuller explanation of reasons. iykyk 👑

💀 TODO 💀

Some of the reported info, such as hex addresses, is not particularly valuable. Other information would be more useful for the typical programmer, such as line-numbers, pad-slot reuses, etc.. Given this, -newlex is not a particularly good flag-name. we said what we said 🙈

👑 AUTHOR 👑

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

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mwah 💋 — this page is from perl v5.42.3, dated 2026-11-03. periodt.