Re^2: keys on scalar warnings and lack thereof

I didn't include %{$_[0]} because it's obviously ok:

perl -MDevel::Peek -e 'Dump(%{$_[0]})'
SV = PVHV(0x157010280) at 0x15700ae40
  REFCNT = 1
  FLAGS = (SHAREKEYS)
  ARRAY = 0x0
  KEYS = 0
  FILL = 0
  MAX = 7

But what is this:

perl -MDevel::Peek -e 'Dump(%$_[0])'  
SV = NULL(0x0) at 0x100939eb8
  REFCNT = 2147483641
  FLAGS = (READONLY,PROTECT)

and this:

perl -MDevel::Peek -e 'Dump(%$^[0])'  
SV = IV(0x159825cf0) at 0x159825d00
  REFCNT = 1
  FLAGS = (PADTMP,IOK,pIOK)
  IV = 5796572328

perl -MDevel::Peek -e 'Dump(%{$^[0]})'
Number found where operator expected (Missing operator before "0"?)
[download]

And all the other weird looking results?

Comment on Re^2: keys on scalar warnings and lack thereof Download Code

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Re^3: keys on scalar warnings and lack thereof by LanX (Saint) on May 14, 2026 at 18:35 UTC
What exactly do you expect from broken code? `$ perl -E' $_[0] = {}; say keys %$_[0]' Experimental keys on scalar is now forbidden at -e line 1. Type of arg 1 to keys must be hash or array (not index/value array sli +ce) at -e line 1, at EOF Execution of -e aborted due to compilation errors.` [download] Please note the not index/value array slice , because that's what's fed into keys. Try `keys %{$_}[0]` and compare the error messages... Update Admittedly, I've never used this before: Index/Value-Array-Slices Cheers Rolf _{(addicted to the Perl Programming Language :) see Wikisyntax for the Monastery}	[reply] [d/l] [select]

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Re^3: keys on scalar warnings and lack thereof
by LanX (Saint) on May 14, 2026 at 18:35 UTC

What exactly do you expect from broken code?

$ perl -E' $_[0] = {}; say keys %$_[0]'
Experimental keys on scalar is now forbidden at -e line 1.
Type of arg 1 to keys must be hash or array (not index/value array sli
+ce) at -e line 1, at EOF
Execution of -e aborted due to compilation errors.
[download]

Please note the not index/value array slice , because that's what's fed into keys.

Try keys %{$_}[0] and compare the error messages...

Update

Admittedly, I've never used this before: Index/Value-Array-Slices

Cheers Rolf
_{(addicted to the Perl Programming Language :)

see Wikisyntax for the Monastery}

[reply]
[d/l]
[select]