Perl 学习手札之十四： Module

LXY3800

　　Modules are collections of Perl code for use with different scripts
　　Modules can be object-oriented or procedural
　　Modules can contain code and/or data

　　
　　Object-oriented vs procedural modules

　　Most modules are object-oriented.

　　object-oriented code has these properties.
　　-Dynamic: the object determines what code to invoke

　　-Encapsulated: the object contains all the code and data it needs

　　-Abstraction: the details may be hidden from the user

　　-Inheritance: One object may inherit properties from another

　　
　　Procedural code has these properties:
　　-simplicity: small subroutines may be coded quickly and easily
　　-Modularity: Functionalities may be used and resused

　　-Linearity: code is clear and readable
　　
　　建立一个module：Example.pm



#Example.pm
#  Example perl module
#

package Example;
use strict;
use warnings;
use IO::File;
our $VERSION = "0.1";
sub new{
    my $class = shift;
    my $self = {};
    bless($self,$class);
    return $self;
}
sub copyfile
{
    my ( $self, $origfile, $newfile ) = @_;
    my $bufsize = 1024 * 1024;
    my $origfh = IO::File->new($origfile, 'r') or die("cannot open $origfile ($!)");
    my $newfh = IO::File->new($newfile, 'w') or die("cannot open $newfile ($!)");
    $origfh->binmode(":raw");
    $newfh->binmode(":raw");
    my $buf = '';
    while( $origfh->read( $buf, $bufsize ) ) {
        $newfh->print( $buf );
    }
    return 1;
}
1;　　这个就是前面的复制文件的代码，现在写到模块里面，注意package关键字。
　　下面就是调用模块的代码：

　　creating.pl



#!/usr/bin/perl
#
use strict;
use warnings;
use Example;
main(@ARGV);
sub main
{
    my $o = Example->new();
    $o->copyfile("olives.jpg","newfile.jpg");
    message("Done.");
}
sub message
{
    my $m = shift or return;
    print("$m\n");
}
sub error
{
    my $e = shift || 'unkown error';
    print("$0: $e\n");
    exit 0;
}　　如前面所示：用了module，代码变得非常简洁，并且可以复用。
　　
　　下面写一个模块：

　　Artist.pm



# Artist.pm
#
# Description goes here
# by Your Name
#

package Artist;
use strict;
use warnings;
our $VERSION = "0.1";
sub new
{
    my $class = shift;
    my $self  = {};
    bless( $self, $class );
    return $self;
}
sub name
{
    my ($self,$name) = @_;
    $self->{name}=$name if defined $name;
    return $self->{name};
}
1;
__END__
=head1 NAME
Template - Description goes here
=head1 SYNOPSIS
    use Template
    my $o = Template->new;
=head1 METHODS
=over 4
=item B<new>
Constructs a new Template object.
Returns a blessed Template object reference.
=item B<method>
Describe the method here
=back
=head1 AUTHOR
Written by Your Name
=head1 HISTORY
    Version history here.
=cut　　在__END__后面的部分是模块的注释。可以根据这个例子学习模块的编写
　　然后调用模块：

　　oodata.pl


#!/usr/bin/perl
#
use strict;
use warnings;
use Artist;
main(@ARGV);
sub main
{
    my $o = Artist->new;
    my $o2=Artist->new;
    $o->name("Jimi Hendrix");
    $o2->name("Miles Davis");
    message($o->name);
    message($o2->name);
    message($Artist::VERSION);
    message($o->VERSION);
}
sub message
{
    my $m = shift or return;
    print("$m\n");
}
sub error
{
    my $e = shift || 'unkown error';
    print("$0: $e\n");
    exit 0;
}　　可以有几种方式初始化模块，然后调用模块。
　　
　　安装模块
　　1. 可以在unix-like系统里面采用下面的方式：
　　1）：在命令行里面输入：sudo cpan 模块名

　　2）：在命令行里面输入perl -MCPAN -e shell， 然后进入CPAN>模式，输入install 模块名，完成安装。
　　3) ：在search.cpan.org里面查找模块，下载相应的tar.gz安装包，然后依次输入：
　　perl MAKEFILE.pl
　　make
　　make test

　　make install
　　然后完成安装。
　　2. 可以在windows系统下面采用下面的方式：
　　选择active perl->perl package manager来在图形界面下选择相应的安装包安装升级

　　注意dependance