Perl 挑战 - 目录迭代器

有时您会听到关于 Perl 的说法，可能有 6 种不同的方法来解决同一问题。优秀的 Perl 开发人员通常具有合理的见解，可以在各种可能的实现方法之间做出选择。

举一个 Perl 问题的例子：

一个简单的脚本，它递归地迭代目录结构，查找最近修改的文件（在某个日期之后，该日期是可变的）。将结果保存到文件中。

对于 Perl 开发人员来说，问题是：完成此任务的最佳方法是什么？

这听起来像是一份工作文件::查找::规则 http://search.cpan.org/perldoc?File::Find::Rule:

#!/usr/bin/perl
use strict;
use warnings;
use autodie;  # Causes built-ins like open to succeed or die.
              # You can 'use Fatal qw(open)' if autodie is not installed.

use File::Find::Rule;
use Getopt::Std;

use constant SECONDS_IN_DAY => 24 * 60 * 60;

our %option = (
    m => 1,        # -m switch: days ago modified, defaults to 1
    o => undef,    # -o switch: output file, defaults to STDOUT
);

getopts('m:o:', \%option);

# If we haven't been given directories to search, default to the
# current working directory.

if (not @ARGV) {
    @ARGV = ( '.' );
}

print STDERR "Finding files changed in the last $option{m} day(s)\n";


# Convert our time in days into a timestamp in seconds from the epoch.
my $last_modified_timestamp = time() - SECONDS_IN_DAY * $option{m};

# Now find all the regular files, which have been modified in the last
# $option{m} days, looking in all the locations specified in
# @ARGV (our remaining command line arguments).

my @files = File::Find::Rule->file()
                            ->mtime(">= $last_modified_timestamp")
                            ->in(@ARGV);

# $out_fh will store the filehandle where we send the file list.
# It defaults to STDOUT.

my $out_fh = \*STDOUT;

if ($option{o}) {
    open($out_fh, '>', $option{o});
}

# Print our results.

print {$out_fh} join("\n", @files), "\n";