Re: The @_ array and the lexical variables

Elements of @_ are aliases to the arguments, i.e. when you change $_[0] directly, you change the original argument, which in this case happens to be $num, respectively %hash.

See perlsub:

The array @_ is a local array, but its elements are aliases for the actual scalar parameters. In particular, if an element $_[0] is updated, the corresponding argument is updated (or an error occurs if it is not updatable).

($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,
[download]

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Re^2: The @_ array and the lexical variables by G4143 (Novice) on Apr 16, 2018 at 11:15 UTC
Could you demonstrate that behaviour with a normal array or how I would arrive at that behaviour? Something like: `my @arr = (my $one, my $two, my $three);` [download]	[reply] [d/l]
Re^3: The @_ array and the lexical variables by choroba (Cardinal) on Apr 16, 2018 at 11:52 UTC
No, it's the magic behind @_ and calling a subroutine that causes the aliasing. Normal arrays don't alias. Another aliasing construct if for: `my $x = 1; for my $y ($x) { $y++; } print $x; # 2` [download] See also Data::Alias . ($q=q:Sq=~/;[c](.)(.)/;chr(-\|\|-\|5+lengthSq)`"S\|oS2"`map{chr \|+ord }map{substrSq`S_+\|`\|}3E\|-\|`7**2-3:)=~y+S\|`+$1,++print+eval$q,q,a, [download]	[reply] [d/l] [select]
Re^4: The @_ array and the lexical variables by G4143 (Novice) on Apr 16, 2018 at 12:08 UTC
OK. Thanks for the clarification.	[reply]
Re^3: The @_ array and the lexical variables by ikegami (Patriarch) on Apr 16, 2018 at 13:27 UTC
`our @arr; local *arr = sub { \@_ }->( my $one, my $two, my $three );` [download] or `use Data::Alias qw( alias ); alias my @arr = ( my $one, my $two, my $three );` [download] or `use feature qw( refaliasing ); my @arr; \$arr[@arr] = \my $one; \$arr[@arr] = \my $two; \$arr[@arr] = \my $three;` [download]	[reply] [d/l] [select]