Perl 学习手札之十四： Module
Modules are collections of Perl code for use with different scriptsModules 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
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