How can I identify and remove redundant code in Perl?

Question

I have a Perl codebase, and there are a lot of redundant functions and they are spread across many files.

Is there a convenient way to identify those redundant functions in the codebase? Is there any simple tool that can verify my codebase for this?

Answer 1

You could use the B::Xref module to generate cross-reference reports.

Answer 2

I've run into this problem myself in the past. I've slapped together a quick little program that uses PPI to find subroutines. It normalizes the code a bit (whitespace normalized, comments removed) and reports any duplicates. Works reasonably well. PPI does all the heavy lifting.

You could make the normalization a little smarter by normalizing all variable names in each routine to $a, $b, $c and maybe doing something similar for strings. Depends on how aggressive you want to be.

#!perl

use strict;
use warnings;

use PPI;

my %Seen;

for my $file (@ARGV) {
    my $doc = PPI::Document->new($file);
    $doc->prune("PPI::Token::Comment");         # strip comments

    my $subs = $doc->find('PPI::Statement::Sub');
    for my $sub (@$subs) {
        my $code = $sub->block;
        $code =~ s/\s+/ /;                      # normalize whitespace
        next if $code =~ /^{\s*}$/;             # ignore empty routines

        if( $Seen{$code} ) {
            printf "%s in $file is a duplicate of $Seen{$code}\n", $sub->name;
        }
        else {
            $Seen{$code} = sprintf "%s in $file", $sub->name;
        }
    }
}