Perl::Critic::Policy::BuiltinFunctions::RequireSimpleSortBlock - Sort blocks should have a single statement.

Perl-Critic documentation Contained in the Perl-Critic distribution.

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NAME

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Perl::Critic::Policy::BuiltinFunctions::RequireSimpleSortBlock - Sort blocks should have a single statement.

AFFILIATION

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

DESCRIPTION

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Conway advises that sort functions should be simple. Any complicated operations on list elements should be computed and cached (perhaps via a Schwartzian Transform) before the sort, rather than computed inside the sort block, because the sort block is called N log N times instead of just N times.

This policy prohibits the most blatant case of complicated sort blocks: multiple statements. Future policies may wish to examine the sort block in more detail -- looking for subroutine calls or large numbers of operations.

CONFIGURATION

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This Policy is not configurable except for the standard options.

AUTHOR

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Chris Dolan <cdolan@cpan.org>

COPYRIGHT

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Copyright (c) 2006-2011 Chris Dolan.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

Perl-Critic documentation Contained in the Perl-Critic distribution. 
##############################################################################
#      $URL: http://perlcritic.tigris.org/svn/perlcritic/trunk/distributions/Perl-Critic/lib/Perl/Critic/Policy/BuiltinFunctions/RequireSimpleSortBlock.pm $
#     $Date: 2011-05-15 16:34:46 -0500 (Sun, 15 May 2011) $
#   $Author: clonezone $
# $Revision: 4078 $
##############################################################################

package Perl::Critic::Policy::BuiltinFunctions::RequireSimpleSortBlock;

use 5.006001;
use strict;
use warnings;
use Readonly;

use Perl::Critic::Utils qw{ :severities :classification };
use base 'Perl::Critic::Policy';

our $VERSION = '1.116';

#-----------------------------------------------------------------------------

Readonly::Scalar my $DESC => q{Sort blocks should have a single statement};
Readonly::Scalar my $EXPL => [ 149 ];

#-----------------------------------------------------------------------------

sub supported_parameters { return ()                                   }
sub default_severity     { return $SEVERITY_MEDIUM                     }
sub default_themes       { return qw( core pbp maintenance complexity) }
sub applies_to           { return 'PPI::Token::Word'                   }

#-----------------------------------------------------------------------------

sub violates {
    my ( $self, $elem, undef ) = @_;

    return if $elem ne 'sort';
    return if ! is_function_call($elem);

    my $sib = $elem->snext_sibling();
    return if !$sib;

    my $arg = $sib;
    if ( $arg->isa('PPI::Structure::List') ) {
        $arg = $arg->schild(0);
        # Forward looking: PPI might change in v1.200 so schild(0) is a PPI::Statement::Expression
        if ( $arg && $arg->isa('PPI::Statement::Expression') ) {
            $arg = $arg->schild(0);
        }
    }
    return if !$arg || !$arg->isa('PPI::Structure::Block');

    # If we get here, we found a sort with a block as the first arg
    return if ( 1 >= $arg->schildren() );

    # more than one child statements
    return $self->violation( $DESC, $EXPL, $elem );
}

1;

#-----------------------------------------------------------------------------

__END__


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