Re^4: perldoc -lf anomaly (%

Ok I was confused about -lf (and -lv and -lq) and my $_ anomaly is pure facepalm. But what about this:

% perldoc -v '%_'
No documentation for perl variable '%_' found

%_ is a special snowflake like $_ and @_ in that they can be used under strict without declaration and they all fail in the same way if you try to own them with my: Can't use global %_ in "my" (but our and local work on all of them). I like using it sometimes in one-liners and dirty scripts cause $_{$_} looks weird and cool and it works good and I like typing it! Anyway I made Claude Haiku 4.5 at duck.ai think about %_ for 36 seconds! I've never seen the robots get so confused. They insist it doesn't exist, or it's nothing special, or that it's a filehandle or a reference to the last call to stat lol:

perl -Mstrict -Mwarnings -le '%_ = ( foo => 1, bar => 2 ); print "$_ =
+ $_{$_}" for keys %_'
[download]

foo = 1
bar = 2

So why isn't it documented? I could swear I saw it somewhere once upon a time, or maybe not... What is it??? Thanks

Comment on Re^4: perldoc -lf anomaly (%_) Download Code

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Re^5: perldoc -lf anomaly (%_) by LanX (Saint) on May 08, 2026 at 10:11 UTC
> So why isn't it documented? Because contrary to $_ and @_ it has no function > I could swear I saw it somewhere once upon a time, or maybe not... People are exploiting the side effect that it's a global and doesn't need to be declared. > What is it??? The typeglob / symbol `_` is global to allow the scalar and array slots $_ and @_ to hold magic. The hash slot is undefined but still global and can be (ab)used for syntactic sugar. Like `# No my/our %_ lives in main:: %_ = (a => 1, b => 2); # global variable in package main` [download] See also this SO discussion https://stackoverflow.com/questions/36723739/undocumented-perl-variable#36724370 Edit `perldoc -v` and `perlvar` should probably be expanded to show a generic explanation for such "reserved" special variables Cheers Rolf _{(addicted to the Perl Programming Language :) see Wikisyntax for the Monastery}	[reply] [d/l] [select]
Re^6: perldoc -lf anomaly (%_) by LanX (Saint) on May 08, 2026 at 12:19 UTC
Follow up: I just noticed that while `@ENV` is reserved special, `@a` is not. Compare `%ENV` and `$a` ... Has this always been the case? I kind of remember @a being "weird" too. `$ perl -e'use strict;@1=(666)' $ perl -e'use strict;@STDOUT=(666)' $ perl -e'use strict;@ENV=(666)' #but $ perl -e'use strict;@a=(42)' Global symbol "@a" req +uires explicit package name (did you forget to declare "my @a"?) at - +e line 1. $ perl -e'print $]' 5.040003$` [download] Cheers Rolf _{(addicted to the Perl Programming Language :) see Wikisyntax for the Monastery}	[reply] [d/l] [select]
Re^7: perldoc -lf anomaly (%_) by choroba (Cardinal) on May 08, 2026 at 12:46 UTC
I think that's because `$a` and `$b` are package variables, not globals. Same with `@F` under `-a`. `map{substr$_->[0],$_->[1]\|\|0,1}[\\|\|{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^ARGV,3]`	[reply] [d/l] [select]
Re^8: perldoc -lf anomaly (%_) by LanX (Saint) on May 08, 2026 at 13:02 UTC
Re^5: perldoc -lf anomaly (%_) by ikegami (Patriarch) on May 08, 2026 at 17:02 UTC
`%_` is a special snowflake like `$_` and `@_` If by special snowflake you mean a punctuation variable, then yes. Yes, `%_` is an invalid names for a lexical, but that's the case for all punctuation variables. Yes, `%_` is strict-exempt, but that's the case for all super-global variables, and all punctuation variables are super-global variables.^[1] So there's nothing special about `%_` specifically, so it makes no sense to document `%_` specifically any more than it does to document `$x`. It works just like every other variable of its class. I could swear I saw it somewhere once upon a time Perl has never used `%_`. Its existence is a side effect of how super-globals are implemented: Symbols are made super-global, not individual variables. This means that `$ENV`, `@2`, `%$` and `&_` all similarly exist as super-global variables. All package variables are visible everywhere, making them all globals. By super-global, I mean that an unqualified reference to this variable looks for the symbol in `main` instead of the current package, so all unqualified references access the same variable regardless of the current package.	[reply] [d/l] [select]

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