in reply to Re^2: perldoc -lf anomaly
in thread perldoc -lf anomaly

These results clearly contradict the perldoc documentation:

That's not true. The docs don't say what happens if you use -l with -f func instead of a module.

Here's another anomaly

What do you think is anomalous? That it's looking up splice instead of $_? That's your error. You interpolated shell variable $_ into your shell command, and it apparently had the value splice.

And another one:

What do you think is anomalous? That output is correct too, and I have no idea what you think is wrong.

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Re^4: perldoc -lf anomaly (%_)
by Anonymous Monk on May 08, 2026 at 09:41 UTC
    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
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      > 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

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        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

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