Re^2: nonempty false list

Hmm thanks to everyone, I definitely see the distinction. What I am TRYING to do is this: I have a hash, and I want to test whether any of three separate keys produce a 'true' value. So, it looks something like this (I boiled it down for the first example)

if(@opts{qw|a b c|})
{

}
[download]

Which seemed pretty elegant, but as previously discussed does not work, because its a hash slice. THIS, however, seems horribly inelegant:

if(@{[@opts{qw|a b c|}]})
{

}
[download]

But perl must have something better than this:

if($opts{a} || $opts{b} || $opts{c})
{

}
[download]

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Re^3: nonempty false list by kennethk (Abbot) on Mar 10, 2011 at 18:52 UTC
Testing each value of a list sounds like a job for grep. When I need to determine if any elements of a list are true, I will usually use something that looks like: `if( grep $_, @opts{qw\|a b c\|}) { }` [download] A cleaner version of this would be `if( grep $opts{$_}, qw\|a b c\|) { }` [download] You can use a couple negations to check if all values are true: `if( !grep !$opts{$_}, qw\|a b c\|) { }` [download] Note that your second suggestion will always return true, since you will always have a 3-element array in scalar context.	[reply] [d/l] [select]
Re^3: nonempty false list by wind (Priest) on Mar 10, 2011 at 18:59 UTC
Just use grep `if (grep {$opt{$_}} qw(a b c)}) {` [download] And you can even capture the keys for which true is returned `if (my @keys = grep {$opt{$_}} qw(a b c)}) { print "@keys match\n";` [download]	[reply] [d/l] [select]
Re^3: nonempty false list by ikegami (Patriarch) on Mar 10, 2011 at 19:06 UTC
There's also List::MoreUtils's `any`. `any { $_ } @opts{qw( a b c )}` [download]	[reply] [d/l] [select]