--- Nicole Seitz <[EMAIL PROTECTED]> wrote:
> Hi there!
>
> I've just started to learn OOP with Perl.With the help of perltoot I wrote a
> class Person and some methods(see below).
'perltoot' is great, but there are a few things that can be done differently.
Admittedly, it's
aimed at beginners, so I can't take *too* much issue with it :)
First, here's what I think is a cleaner way of writing the constructor:
sub new {
my $class = shift;
my %self = map {$_ => undef} qw(CNAME SNAME STREET CITY PHONE EMAIL);
return bless \%self, $class;
}
Note how that compares to the following:
> sub new {
> my $self = {};
> my $proto = shift;
> my $class = ref($proto) || $proto;
> $self->{CNAME} = undef;
> $self->{SNAME} = undef;
> $self->{STREET} = undef;
> $self->{CITY} = undef;
> $self->{PHONE} = undef;
> $self->{EMAIL} = undef;
>
> bless ($self, $class);
> return $self;
> }
The "ref($proto) || $proto" line, unfortunately, should *not* be there. All it does
is allow you
to call a constructor on an instance of an object. Typically, that's useful if you
want to clone
an object (create a new object with the same properties), but that's not being done
here and
should be left out.
> sub cname {
> my $self = shift;
> if (@_) {$self->{CNAME} = shift }
> return $self->{CNAME};
> }
[snip]
> To store some data in my object I did the follwing:
>
> use Person;
>
> $myPerson = Person->new();
> $myPerson->cname("John");
> $myPerson->sname("Smith");
> $myPerson->street("Euston Road");
> $myPerson->city("London");
> $myPerson->phone("414 3344");
>
> Do I really need all these methods?
Probably. You can rewrite your constructor to handle these properties, but later if a
person
changes their phone number, you'll want a way to change it. Another way to write the
constructor
is to assign the arguments when you run the program:
sub new {
my $class = shift;
my %self = map { $_ => @_ ? shift : undef }
qw(CNAME SNAME STREET CITY PHONE EMAIL);
return bless \%self, $class;
}
That's bad, though, because there's no data validation. It's just an example. Change
the
constructor as above and you can test it:
use Data::Dumper;
$myPerson = Person->new(
'John',
'Public',
'123 Main Street',
'Portland',
'Oregon',
'[EMAIL PROTECTED]'
);
print Dumper $myPerson;
In reality, I would use named arguments to the constructor and test them for validity
before
assigning them. They should be tested for validity in the constructor, though, and
*not* in your
code that calls them. That way, when you reuse the object, you don't need to worry
about whether
or not you forgot to test your args.
Cheers,
Ovid
=====
"Ovid" on http://www.perlmonks.org/
Web Programming with Perl: http://users.easystreet.com/ovid/cgi_course/
Silence Is Evil: http://users.easystreet.com/ovid/philosophy/decency.txt
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