Re: Smartmatch alternatives

[dcmertens]

I believe the answer to your question is "no". At least, I can't think of a clean looking way using normal Perl syntax to do it, unless you are willing to use a function call. On the other hand, if you are willing to use a function call, your code becomes self-documenting. In an effort to aggravate BrowserUK, I present both a normal function and a pipelining function ref for your consideration:

use strict;
use warnings;
use Test::More;

my @data = ('1.0', 'hello', 0);

sub is_string_in {
    my $number_to_find = shift;
    return 0 < (grep { $_ eq $number_to_find } @_);
}
my $is_string_in = \&is_string_in;

ok('hello'->$is_string_in(@data));
ok(is_string_in('hello' => @data));

ok(not 1->$is_string_in(@data));
ok(not is_string_in(1 => @data));

ok(0->$is_string_in(@data));
ok(is_string_in(0 => @data));


use Scalar::Util qw(looks_like_number);
sub is_number_in {
    my $number_to_find = shift;
    return unless looks_like_number($number_to_find);
    return 0 < (grep { looks_like_number($_) and $_ == $number_to_find
+ } @_);
}
my $is_number_in = \&is_number_in;

ok(not 'hello'->$is_number_in(@data));
ok(not is_number_in('hello', @data));

ok(1->$is_number_in(@data));
ok(is_number_in(1, @data));

ok(0->$is_number_in(@data));
ok(is_number_in(0, @data));

done_testing;

[oiskuu]

Or, avoiding full grep:

  my $contains = sub { $_ eq $_[1] && return 1 for @{$_[0]}; 0 };

  for (qw( Lisa Bart Fred LanX )) {
    [qw( Fred Wilma Barney Betty )]->$contains($_) and print;
  }

Though efficiency probably shouldn't enter the discussion here. Performing a key search on array, where you could have used a hash—bad decision. Another reason to dislike the smartmatch: it promotes bad design.

[tobyink]

It makes sense to use hash keys if all the items being searched through are strings. If some of them are regexps, coderefs, objects with overloading, etc., then a hash is not an option.