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Postings from September 2000
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=head1 TITLE
smart container slicing
=head1 VERSION
Maintainer: David Nicol <perl6rfc@davidnicol.com>
Date: 1 September 2000
Mailing List: perl6-language-data@perl.org
Version: 1
Number: 191
Status: Developing
=head1 ABSTRACT
a more concise syntax for matching all the elements in a container that
are stored under keys that meet a condition
=head1 DESCRIPTION
What if, instead of requiring
@onesIwant = @hash{grep /restriction on keys/ keys %hash};
one could simply write
@onesIwant = @hash{/restriction on keys/};
to obtain a list of all items stored in C<hash> under keys containing
the string C<'restriction on keys'>
=head1 IMPLEMENTATION
When interpreting the appearance of a single regex (including an object
resulting from a C<qr//>) inside braces indicating container lookup,
in a "slicing" context, the regex is applied to the keys of the container
and the matching elements are returned, as per the longer syntax involving
an intermediate anonymous array.
=head1 CONFLICTS
In situations where one wants to pull a list of one item
out of a hash in which that item is keyed with a regex, assuming such
is possible, one will need to use
@listofoneitem = ( $hash{$regex} );
instead of the syntax appropriated by this suggestion.
=head1 BUT WAIT THERE'S MORE
With the addition to the language of regular expression syntax to
deal numbers by value rather than is done now, the syntax described
in this document may provide a concise way to slice multidimensional
containers.
=head1 REFERENCES