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SUPER example
More Objects example from a Well House Consultants training course
More on More Objects [link]
Source code: oo6 Module: P218
use strict;
{ package trainjourney; our @ISA = ("journey"); sub getroute { my ($current) = @_; return "By train from ". $current->{from} . " to " . $$current{to}; } # SUPER looks for method in parent class via the ISA route # Here's an example - "I want to do what the base class does with an extra bit" sub getarrival { my ($current) = shift; my $excuse = $current->SUPER::getarrival(@_); return "$excuse ... but LATE!\n"; } } { package busjourney; our @ISA = ("journey"); sub getroute { my ($current) = @_; return "By bus from ". $current->{from} . " to " . $$current{to}; } } { package journey; sub new { my ($class,$from,$to,$deptime,$mins,$capa) = @_; my %info; $info{from} = $from; $info{to} = $to; $info{deptime} = $deptime; $info{mins} = $mins; $info{capa} = $capa; bless \%info,$class; } # Melksham Devizes 08:40 16 81 road # factory method sub build { my ($properties) = @_; my ($from, $to, $deptime, $mins, $capa, $mode) = split(/\s+/,$properties); if ($mode eq "rail") { return (new trainjourney($from, $to, $deptime, $mins, $capa)); } elsif ($mode eq "road") { return (new busjourney($from, $to, $deptime, $mins, $capa)); } die "Data is screwed up - $properties\n"; } sub getarrival { my ($current) = @_; my $result = $$current{deptime} . "+" . $$current{mins}; return $result; } sub getroute { my ($current) = @_; # On "from" and "to" - different syntax for same type of access! return $current->{from} . " to " . $$current{to}; } sub longer { my ($this,$that) = @_; ( $this->getmins() > $that->getmins() ) ? $this : $that; } sub longest { my ($sofar,@maybes) = @_; foreach my $tryme (@maybes) { $sofar = $sofar->longer($tryme); } $sofar; } sub get { my ($current,$prop) = @_; return $current->{$prop}; } sub set { my ($current,@others) = @_; my $fp = $others[0]; my %params; if (ref($fp) eq "HASH") { %params = %$fp; } else { die ("That's odd") if (@others % 2); %params = @others; } foreach my $k (keys(%params)) { my $k9 = $k; $k9 =~ s/^-//; $current->{$k9} = $params{$k}; } return 1; } sub AUTOLOAD { my ($current,@others) = @_; our $AUTOLOAD; # like a "no strict" for the one variable! # contents are ... journey::getfrom ... or similar! my ($key,$property) = $AUTOLOAD =~ /.*:(...)(.*)/; if ($key eq "get") { return $current->{$property}; } if ($key eq "set") { return $current->{$property} = $_[1]; } } } no strict; push @options, new trainjourney("Melksham","Trowbridge","06:40",12,150); push @options, new busjourney("Melksham","Bath","07:12",42,61); push @options, new trainjourney("Melksham","Swindon","07:17",25,75); push @options, new busjourney("Melksham","London","07:45",150,81); push @options, new busjourney("Melksham","Easterton","19:25",35,53); $source = <<DONE; Melksham Devizes 08:40 16 81 road Melksham Calne 14:10 18 61 road Melksham Cheltenham 19:47 63 140 rail Melksham Southampton 19:11 83 150 rail DONE @extras = split(/\n/,$source); # represents data from a file! # factory method - will build me an object of some type or other!! foreach $addition (@extras) { push @options,journey::build($addition); } $options[4] -> set(comment => "near to home", -from => "Bowerhill", deptime => "19:29", mins => 31); %lundun = ("from","Sells Green","to","Victoria"); $options[3] -> set(\%lundun); foreach $j (@options) { print "Leaving from ",$j->getfrom()," and going to ",$j->getto(),"\n"; print $j->getroute()," arrives at ",$j->getarrival(),"\n"; print $j->getmins(),"\n"; print $j->get("comment"),"\n\n"; } $dis = $options[0]; $dat = $options[1]; sub handle { my ($obj) = @_; print "How about a trip to ",$obj->getto(),"\n"; } # ugle psuedo-code ... handle the longer one # if ($dis->longer($dat)) { # handle($dis); # } else { # handle($dat); } # Better - handle the longer ("most appropriate") one # These are dynamic (object) methods running on a class MEMBER (passing in another) $approp = $dis->longer($dat); handle($approp); $approp = $dat->longer($dis); handle($approp); # This is a static (class) methods running in the class AS A WHOLE # (we can't be sure that there's a member to run it on and we want symmetry in the list) $approp = journey::longest(@options); handle($approp); __END__ Sample data wizard:pl graham$ perl oo6 Leaving from Melksham and going to Trowbridge By train from Melksham to Trowbridge arrives at 06:40+12 ... but LATE! 12 Leaving from Melksham and going to Bath By bus from Melksham to Bath arrives at 07:12+42 42 Leaving from Melksham and going to Swindon By train from Melksham to Swindon arrives at 07:17+25 ... but LATE! 25 Leaving from Sells Green and going to Victoria By bus from Sells Green to Victoria arrives at 07:45+150 150 Leaving from Bowerhill and going to Easterton By bus from Bowerhill to Easterton arrives at 19:29+31 31 near to home Leaving from Melksham and going to Devizes By bus from Melksham to Devizes arrives at 08:40+16 16 Leaving from Melksham and going to Calne By bus from Melksham to Calne arrives at 14:10+18 18 Leaving from Melksham and going to Cheltenham By train from Melksham to Cheltenham arrives at 19:47+63 ... but LATE! 63 Leaving from Melksham and going to Southampton By train from Melksham to Southampton arrives at 19:11+83 ... but LATE! 83 How about a trip to Bath How about a trip to Bath How about a trip to Victoria wizard:pl graham$ Learn about this subject
This module and example are covered on the following public courses:
* Perl Programming * Perl for Larger Projects * Learning to program in Perl * Perl Programming Also available on on site courses for larger groups Books covering this topic
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Other Examples
This example comes from our "More Objects" training module. You'll find a description of the topic and some
other closely related examples on the "More Objects" module index page.
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