[doc] perldata hash slice example will blow up if used for more than depth 1

[jidanni]

perldata says

Since you can assign to a list of variables, you can also assign to an array or hash slice ...

@colors{'red','blue','green'} = (0xff0000, 0x0000ff, 0x00ff00);

The previous assignments are exactly equivalent to ...

($colors{'red'}, $colors{'blue'}, $colors{'green'}) = (0xff0000, 0x0000ff, 0x00ff00);

OK, but it needs to mention more than just one depth,

@{$colors{favorites}}{ 'red', 'blue', 'green' } #OK

Else users will extend the analogy presented, and assume

@colors{favorites}{ 'red', 'blue', 'green' } #syntax error

will work !

Also mention there is no way to use a consistent syntax for first vs.
more layers.

[khwilliamson]

@jdanni, I'm trying to fix this, but I'm not good with slices. I don't understand what you mean

Also mention there is no way to use a consistent syntax for first vs.
more layers.

I'm happy to add your first example about needing to enclose @colors{favorites} with braces

[jidanni]

Thanks but we will need a third person who is good with slices that go deeper than just one level to step in and interpret what I meant back in 2020 when I was slightly better with slices myself.

[guest20]

% export LC_ALL=en_AU 
% perl -MData::Dumper -E'
  my %colours;  
  @{ $colours{favourites} }{ 'red', 'blue', 'green' } = qw/r b g /; 
  say +Dumper+ \%colours 
' 
$VAR1 = {
    'favourites' => {
        'green' => 'g',
        'blue' => 'b',
        'red' => 'r'
    }
};

[Grinnz]

The request is that, when you are trying to slice an array or hash that is within another array or hash, you need to use the brace syntax (or postfix dereference syntax) to dereference $colors{favorites} as a list slice, because a naive @colors{favorites}{ 'red', 'blue', 'green' } as suggested will dereference the favorites key as a scalar and not a list slice (and then be a syntax error because of the @).

[Grinnz]

Or put another way, the hash you are trying to slice is $colors{favorites}, not %colors, so you cannot apply the @ sigil directly to %colors to do it.