"R. Joseph Newton" wrote:
>
> But...
>
> I can do this:
>
> #!/usr/bin/perl -w
>
> use strict;
>
> use Person;
>
> my $person = Person::new("Newton", "R. Joseph");
> $person->set_address("666 NoSpam way", "Eugene", "OR", "97402",
> "USA");
> $person->{'Surname'} = "Johnson"; #this
> $person->print_name();
> $person->{'What the heck'} = "Jeez, this is a porous guy!"; # and this
> print "$person->{'What the heck'}\n";
>
> Without anything preventing me. I am not at all sure that this is a good thing. Is
> there any way to construct a class so that member data stays private? This was the
> factor that kept me from venturing into Perl OOP, and it still seems like it could
> lead to problems if the only thing preventing this kind of external access is the
> injuction "Don't do that!".
>
> Joseph
>
Got it! The changes shown below seem to provide the protection I want. I guess the
object hash can be left as a programmer scratchpad, while the payload remains
protected as a private variable
> package Person;
>
> use strict;
> use warnings;
> use Address;
>
> my ($surname, $given_name, $address);
>
> sub new {
> my $self = {};
> set_name(@_);
> bless $self;
> }
>
> sub set_name {
> my $self = shift;
> ($surname, $given_name) = @_;
> }
>
> sub print {
> my $self = shift;
> print "$surname, ";
> print "$given_name\n";
> return unless defined $address;
> $address->print();
> }
>
> sub set_address {
> my $self = shift;
> $address = Address::new(@_);
> }
>
> my $motto = "Every man, woman and child is a star";
> __END__
>
Results before change:
E:\d_drive\perlStuff>PersonTest.pl
Johnson, R. Joseph # Name has been corrupted by wayward code
666 NoSpam way
Eugene, OR 97402
USA
Jeez, this is a porous guy!
After:
Newton, R. Joseph # Still intact
666 NoSpam way
Eugene, OR 97402
USA
Jeez, this is a porous guy!
With an additional line to demonstrate proper modification by object methods:
#!/usr/bin/perl -w
use strict;
use Person;
my $person = Person::new("Newton", "R. Joseph");
$person->set_address("666 NoSpam way", "Eugene", "OR", "97402",
"USA");
$person->{'Surname'} = "Johnson"; # Still here, but doesn't touuch the payload
$person->set_name("Clinton", "William"); # Safe modification--uses object method
$person->print();
$person->{'What the heck'} = "Jeez, this is a porous guy!";
print "$person->{'What the heck'}\n";
And the output:
Clinton, William
666 NoSpam way
Eugene, OR 97402
USA
Jeez, this is a porous guy!
I like it.
Joseph
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