How do you write wrapper module? - perl

Question

I'm writing a download sub module, I would like it looks like this:
Download.pm
Download/Wget.pm
Download/LWP.pm
Download/Curl.pm
Download/Socket.pm
My Download.pm should provide an api sub download($url). It will look for LWP module, then wget command, then curl command, if non of these exist, it will use Socket.
How can I write wrapper module?

Answer 1

Here is some example, how i did it:
How it works? It checks for some condition, and creates object depends on this condition. And subroutine also checks for reference type and calls the right method
file /tmp/Adapt/Base.pm (base module):
#!/usr/bin/perl
package Adapt::Base;
use strict;
use warnings;
sub new {
my $class = shift;
my $self;
if ( time % 3 ) {
require "/tmp/Adapt/First.pm";
$self = \Adapt::First->new(#_);
}
elsif ( time % 2 ){
require "/tmp/Adapt/Second.pm";
$self = \Adapt::Second->new(#_);
}
else {
require "/tmp/Adapt/Default.pm";
$self = \Adapt::Default->new(#_);
}
bless( $self, $class );
}
sub somesub {
my $s = shift;
my $self = $$s;
if ( ref( $self ) eq 'Adapt::First' ) {
$self->firstsub();
}
elsif ( ref( $self ) eq 'Adapt::Second' ) {
$self->secondsub();
}
else {
$self->defaultsub();
}
}
1;
file /tmp/Adapt/First.pm (some module):
#!/usr/bin/perl
package Adapt::First;
use strict;
use warnings;
sub new {
my $class = shift;
my $self = {};
bless( $self, $class );
}
sub firstsub {
print "I am 1st sub.\n";
}
1;
file /tmp/Adapt/Second.pm (another module):
#!/usr/bin/perl
package Adapt::Second;
use strict;
use warnings;
sub new {
my $class = shift;
my $self = {};
bless( $self, $class );
}
sub secondsub {
print "I am 2nd sub.\n";
}
1;
and file /tmp/Adapt/Default.pm (default module):
#!/usr/bin/perl
package Adapt::Default;
use strict;
use warnings;
sub new {
my $class = shift;
my $self = {};
bless( $self, $class );
}
sub defaultsub {
print "I am default sub.\n";
}
1;
and test script:
#!/usr/bin/perl
use strict;
use warnings;
require '/tmp/Adapt/Base.pm';
for (0..10) {
my $test = Adapt::Base->new;
$test->somesub;
sleep 1;
}
output:
dev# perl /tmp/adapt.pl
I am default sub.
I am 1st sub.
I am 1st sub.
I am 2nd sub.
I am 1st sub.
I am 1st sub.
I am default sub.
I am 1st sub.
I am 1st sub.
I am 2nd sub.
I am 1st sub.
dev#