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Example of OO in Perl
Although Perl 5 doesn't use the words "class", "method" or "object" (or any of the other common OO words), it never the less has a very good OO model indeed - here's the source code of an example, together with the result of running the sample. I'll then give you a few clues!
use train;
use bus;
push (@ptl, new train("07:17",2,75));
push (@ptl, new train("06:40",3,60));
push (@ptl, new bus("07:12",2,40));
push (@ptl, new bus("08:10",1,61));
for $tranbit (@ptl) {
print $tranbit;
print " ",$tranbit->getstaff();
print " ",$tranbit->getcapacity();
print " ",$tranbit->getwhat();
print "\n";
}
__END__
The stuff below is comments as held in this
file. Split it out to separate files if you
want to run it!
############### train.pm
package train;
use pt;
@ISA = ("pt");
sub getstaff {
return 1;
}
sub getwhat {
return ("Metal wheeler");
}
1;
############### bus.pm
package bus;
use pt;
@ISA = ("pt");
sub getstaff {
my ($self) = @_;
return $$self{nv};
}
sub getwhat {
return ("Rubber wheeler");
}
1;
####################### pt.pm
package pt;
sub new {
my($class,$time,$nv,$vc)=@_;
my %info;
$info{time} = $time;
$info{nv} = $nv;
$info{vc} = $vc;
bless \%info,$class;
}
sub getcapacity {
my ($self) = @_;
return $$self{nv}*$$self{vc};
}
1;
################## Runs as ...
j8pl grahamellis$ perl tharness
train=HASH(0x801c70) 1 150 Metal wheeler
train=HASH(0x815f60) 1 180 Metal wheeler
bus=HASH(0x815f9c) 2 80 Rubber wheeler
bus=HASH(0x815ff0) 1 61 Rubber wheeler
j8pl grahamellis$
Right. Now ...
A Perl package is a class
A Perl sub is used to define a method
The list @ISA defines inheritance
Perl's bless function defines the container for variables in the object
my defines a locally scoped variable
-> is used to invoke a method on an object (written 2008-06-03 17:32:36)
Associated topics are indexed under P213 - Perl - Creating your own ClassesP218 - Perl - More Objects
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