Perl::Critic::Policy::BuiltinFunctions::ProhibitComplexMappings3pm

Affiliation

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

Overview

The map function can be confusing to novices in the best of circumstances. Mappings with multiple statements are even worse. They're also a maintainer's nightmare because any added complexity decreases readability precipitously. Why? Because map is traditionally a one-liner converting one array to another. Trying to cram lots of functionality into a one-liner is a bad idea in general.

The best solutions to a complex mapping are: 1) write a subroutine that performs the manipulation and call that from map; 2) rewrite the map as a for loop.

Caveats

This policy currently misses some compound statements inside of the map. For example, the following code incorrectly does not trigger a violation:

    map { do { foo(); bar() } } @list

Configuration

By default this policy flags any mappings with more than one statement. While we do not recommend it, you can increase this limit as follows in a .perlcriticrc file:

    [BuiltinFunctions::ProhibitComplexMappings]
    max_statements = 2

Credits

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