What is a hash slice and how is one written in Perl?

A means of selecting multiple elements for fetching or setting. An example would be @hash{ 'key1', 'key2', ... }. See perldata for details.

if a delete function in a Perl program specifies a slice, will the interpreter break it up into individual calls to DELETE?

Yes.

{
   package Tester;
   use Tie::Hash qw();
   our @ISA = 'Tie::StdHash';
   sub DELETE {
      my $self = shift;
      print("DELETE @_\n");
      $self->SUPER::DELETE(@_)
   }
}

{
   tie my %hash, 'Tester';
   %hash = (
      a => 1,
      b => 2,
      c => 3,
      d => 4,
   );
   delete @hash{qw( b c )};
   print(join(' ', keys %hash), "\n");
}
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DELETE b
DELETE c
a d
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If there are other pages that cover this subject, please tell me.

• tie
• Tie::Scalar
• Tie::Array
• Tie::Hash
• Tie::Handle

Update: Formatting changes. Switched from using array to using hash in DELETE test.