Re^3: keys on scalar warnings and lack thereof

I didn't explain %{ $_[0] }; I explained why %$_[0] is nonsense.

Maybe adding spaces and parens will help?

keys( %$_ )         
keys( %$_ ) [0]     Nonsense
keys( %$ ); [0]     `;` = End of statement
keys( %$ )  # [0]   `#` = Comment
keys( %$ ) ^ [0]    `^` = Binary op
keys( %$ ) & [0]    `&` = Binary op
keys( %$ ) = [0]    `=` = Binary op
keys( %$ ) | [0]    `|` = Binary op
keys( %$ ), [0]     `,` = Binary op
keys( %$ ) < [0]    `<` = Binary op
keys( %$ ) > [0]    `>` = Binary op
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Re^4: keys on scalar warnings and lack thereof by LanX (Saint) on May 18, 2026 at 10:19 UTC
> I explained why `%$_[0]` is nonsense Please note that since 5.20 this alone is no nonsense anymore. Though applying `keys` on it is not allowed/making sense. See my last post > `keys( %$_ ) [0]` Nonsense This is not what happens, but `keys ( %{$_}[0] )` Update Demo in debugger `$perl -db0 ... DB<4> $_ = [ qw/a b c d/ ] DB<5> x %$_[0,2,1] 0 0 1 'a' 2 2 3 'c' 4 1 5 'b' DB<6> say %$_[0,2,1] 0a2c1b DB<7> p $] 5.040003` [download] Cheers Rolf _{(addicted to the Perl Programming Language :) see Wikisyntax for the Monastery}	[reply] [d/l] [select]

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Re^4: keys on scalar warnings and lack thereof
by LanX (Saint) on May 18, 2026 at 10:19 UTC

> I explained why %$_[0] is nonsense

Please note that since 5.20 this alone is no nonsense anymore.

Though applying keys on it is not allowed/making sense.

See my last post

> keys( %$_ ) [0] Nonsense

This is not what happens, but

keys ( %{$_}[0] )

Update

Demo in debugger

$perl -db0
...
  DB<4> $_ = [ qw/a b c d/ ]

  DB<5> x %$_[0,2,1]
0  0
1  'a'
2  2
3  'c'
4  1
5  'b'
  DB<6> say %$_[0,2,1]
0a2c1b
  DB<7> p $]
5.040003
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Cheers Rolf
_{(addicted to the Perl Programming Language :)

see Wikisyntax for the Monastery}

[reply]
[d/l]
[select]