I don't see why that would be good practice.

Let's create a telephone class:

package Example::Phone {
  use Moo;
  has number => (is => 'ro', required => 1);
  sub call { ... }
}

[download]

Now let's use it:

use Example::Phone;

my $dad = Example::Phone->new(number => '+44 123 456 7890');
say "Dad's number is ", $dad->number;
$dad->call();

[download]

The object is immutable, in that once it's been instantiated, you can't use its public API to alter the number string.

But that shouldn't stop us from subclassing it:

package Example::Phone::Mobile {
  use Moo;
  extends 'Example::Phone';
  sub send_sms { ... }
}

[download]

It doesn't in any way compromise the immutability of the parent class.

In reply to Re^3: Perl OOP by tobyink
in thread Perl OOP by QueenSvetlana

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