First OOP programme

[Zhris]

Hello,

I was recently inspired by a recent thread (

http://www.tek-tips.com/viewthread.cfm?qid=1639030&page=1)

to expand my skills in Perl, and begin to programme using OOP. I have read example code in my time, but never applied my knowledge. I decided I would create my first OOP programme, which is a simple script designed to create and manipulate "user profiles". Its working pretty well, but theres alot I still don't know / understand.

1) I'm a little confused with namespacing, specifically $class and $self. I have seen the first arguement been assigned to $class in one script, but the first arguement been assigned to $self in another similar script. The way I figured it was to use $class when creating a new object, then $self from then on. Does this make sense?

2) At the end of my code, I have commented out a section. Basically, if I want to print out every 'name' in @foundpeople, I could easily do "print $_->{'name'}, '<br />' foreach (@foundpeople);", but this breaks away from complete OOP. I could create another method but it wouldn't be as practical as to do it the way I have commented out. Somehow I need to bless $person into some class when constructing the object data, but i'm baffled on what to do. How could I get my commented section of code to work as expected ($person becomes a class), ignoring the dummy methods which I haven't created yet?

3) In order to have as much freedom as possible whilst manipulating data, I have been creating sub routine references as arguements. I have never seen it done this way, but I couldn't think of a better way. It works well, but is there a better, more useable / readable way to do it i.e. having to use $_[0] is pointless right, because all the method needs to know is e.g. 'name'?

I'm sorry if I haven't been clear enough, but its kind of difficult to explain when my knowledge is limited. I would appreciate any advice / improvements etc.

Thank you very much,

Chris

#//////////////////////////////////////////////////

#!/usr/bin/perl
use strict;
use warnings;
use CGI ':standard';
use CGI::Carp qw(fatalsToBrowser warningsToBrowser);
print "Content-type: text/html\n\n";
warningsToBrowser(1);

#//////////////////////////////////////////////////

package profilePeople;

use strict;
use warnings;
use Data::Dumper;

sub new { #input=hash ref(s), output=object
	my $class = shift;
	my @people = @_;
	my $self = [];
	my $return = bless $self, $class;
	$return->newPeople(@people);
	return $return;
}

sub newPeople { #input=hash ref(s), output=array ref
	my $self = shift;
	my @people = @_;
	my $return = [];
	foreach my $person (@people) {
		#push @$self, (bless $person, ?);
		push @$self, $person;
		push @$return, $person;
	}
	return $return;
}

sub updatePeople { #input=hash ref then subroutine ref, output=array ref
	my $self = shift;
	my $update = shift || {};
	my $condition = shift || sub{1};
	my $return = [];
	foreach my $index (0 .. $#$self) {
		if (&$condition($$self[$index])) {
			while (my ($key, $value) = (each %$update)) {
				#if ($value eq '') { delete $$self[$index]{$key}; next; }
				$$self[$index]{$key} = $value;
				push @$return, $$self[$index];
			}
		}
	}
	return $return;
}

sub deletePeople { #input=subroutine ref, output=array ref
	my $self = shift;
	my $condition = shift || sub{1};
	my $return = [];
	foreach my $index (0 .. $#$self) {
		if (&$condition($$self[$index])) {
			push @$return, $$self[$index];
			delete $$self[$index];
		}
	}
	return $return;
}

sub findPeople { #input=subroutine ref, output=array ref
	my $self = shift;
	my $condition = shift || sub{1};
	my @return = grep { &$condition($_) } @$self;
	return \@return;
}

sub dumpIt { #input=ref, output=scalar
	my $self = shift;
	my $return = Dumper($self);
	return $return;
}

#//////////////////////////////////////////////////

#$object->updatePeople({'name' => 'newname', 'age' => '', 'location' => 'UK'}); #no 2nd arg = update everyone
#$object->deletePeople(); #no args = delete everyone
#my @foundpeople = @{$object->findPeople()}; #no args = find everyone

my $object = profilePeople->new({'name' => 'peter'}, {'name' => 'william'});
$object->newPeople({'name' => 'chris', 'age' => '20', 'sex' => 'male'}, {'name' => 'john', 'age' => '44', 'sex' => 'male'});
$object->newPeople({'name' => 'laura', 'age' => '22', 'sex' => 'female'});
$object->updatePeople({'name' => 'newname', 'age' => '', 'location' => 'UK'}, sub{$_[0]{'name'} eq 'chris'});
$object->deletePeople(sub{$_[0]{'name'} =~ m/^laura|john$/i});
my @foundpeople = @{$object->findPeople(sub{($_[0]{'age'} > 21) || ($_[0]{'name'} =~ m/W/i)})};

print $_->{'name'}, '<br />' foreach (@foundpeople);
print $object->dumpIt;

#foreach my $person (@foundpeople) {
#	my @keys = $person->personKeys('22');
#	my @values = $person->personValues('name', 'age');
#}

#//////////////////////////////////////////////////

 

[Zhris]

Hello,

I just wanted to clarify that I figured out 2), I was able to create multiple blessed objects within an existing blessed object. I am not entirely clear yet, but I think they are known as instances. Initially I was trying to bless '$person' to some class that didn't exist (yet), but I figured that doing 'bless $person', without a 2nd arg created an "instance" in the current package.

I have just pulled out my O'Reilly Intermediate Perl book, which has tonnes of useful information, which i'm going to have a further read of, although its a little difficult to follow their "zoo" example, mainly because its not a very well applied example.

Chris

 

[Zhris]

Hello,

Last reply to close this thread. I have since refined my code and all my queries were answered on another forum. I always post on Tek-Tips first because the members, particularly in the Perl forum, are extremely talented, and have helped me tremendously. Reading back my original post, I can see that I asked a couple of silly questions and I was very unclear.

Thanks,

Chris