Perl::Critic::Policy::BuiltinFunctions::ProhibitBooleanGrep3pm

Affiliation

This Policy is part of the core Perl::Critic distribution.

Overview

Using "grep" in boolean context is a common idiom for checking if any elements in a list match a condition. This works because boolean context is a subset of scalar context, and grep returns the number of matches in scalar context. A non-zero number of matches means a match.

But consider the case of a long array where the first element is a match. Boolean "grep" still checks all of the rest of the elements needlessly. Instead, a better solution is to use the "any" function from either List::Util, List::SomeUtils, or List::MoreUtils. The "any" function will return as soon as a successful match is found, rather than processing the entire list. This saves time.

Configuration

This Policy is not configurable except for the standard options.

Caveats

The algorithm for detecting boolean context takes a LOT of shortcuts. There are lots of known false negatives. But, I was conservative in writing this, so I hope there are no false positives.

Credits

Initial development of this policy was supported by a grant from the Perl Foundation.