deleting multiple hash keys

cosmicperl has asked for the wisdom of the Perl Monks concerning the following question:

Hi All,
I've come across a code technique I couldn't find documented anywhere. It's a clever way of deleting multiple hash keys:-

my %hash = ( a => 1, b => 2, c => 3 );
delete @hash{qw/a b/};
[download]

I don't fully understand why the @ is used. I guess because the qw is returning multiple values.
I was hoping someone could tell me what this is called, point me onto the right docs, or maybe even show similar clever hash techniques.

Lyle

Comment on deleting multiple hash keys Download Code

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Re: deleting multiple hash keys by zwon (Abbot) on Feb 28, 2009 at 20:26 UTC
You should read about Slices.	[reply]
Re^2: deleting multiple hash keys by AnomalousMonk (Archbishop) on Mar 01, 2009 at 03:10 UTC
And with reference to delete, quoth the docs (emphasis added): delete EXPR Given an expression that specifies a hash element, array element, hash slice, or array slice, deletes the specified element(s) from the hash or array.	[reply]
Re: deleting multiple hash keys by Lawliet (Curate) on Mar 01, 2009 at 00:27 UTC
As you already know, scalars are a single value and are represent by a dollar sign. This is why when accessing one value from a hash you use the dollar sign. '@' is associated with multiple values (specifically, arrays, which are multiple scalars). Thus, when accessing multiple scalars from a hash, you use the @ sign. I believe this is changing in Perl 6 due to the confusion it brings. And you didn't even know bears could type.	[reply]
Re: deleting multiple hash keys by shmem (Chancellor) on Mar 01, 2009 at 14:10 UTC
See Re: meaning of '@' sigil on a hash?	[reply]
Re: deleting multiple hash keys by cosmicperl (Chaplain) on Mar 04, 2009 at 20:02 UTC
Thanks everyone! I'd used slices before on arrays, but didn't realise you could apply them to hashes.	[reply]