Re: Creating Common Constructor

You could use a 'factory method' to keep track of the objects you create e.g

sub Zoo::factory {
  my($self, $class, $args) = @_;

  my $obj = "Zoo::Animal::$class"->new( $args );
  $self->{"_${class}_count"}++;

  return $obj;
}

my $zoo   = Zoo->new;
my $camel = $zoo->factory("Camel");
[download]

That code isn't complete or tested but it should give you some idea of how to go about implementing a factory method.
HTH

_________ broquaint

Comment on Re: Creating Common Constructor Download Code

Replies are listed 'Best First'.
Re: Re: Creating Common Constructor by themage (Friar) on Jul 13, 2003 at 12:44 UTC
I like this, but I would implement this with a small difference: sub Zoo::factory { my ($self, $class, @args)=@_; my $obj="Zoo::Animal::$class"->new(@args); $self->{count}->{$class}++; return $obj; } my $zoo=Zoo->new(); my $camel=$zoo->factory("Camel"); I would implement this difference so I could use $zoo->{zbr} for something else, and would be easier to find the counts to every specie in the $Zoo, 'cause every key in the %{$zoo->{count}} would be a diferent specie. The other way I think I could implement was without a factory method, but with a adquire method, with some changes: #Zoo.pm file sub new { ... $self->{animals}=[]; ... } sub adquire { my $self=shift; push @{$self->{animals}}, @_; } sub count { my $self=shift; my %count=(); for my $anim (@{$self->{animals}}) { $count{$anim->specie()}++; } return %count; } #Zoo/Animal.pm ... sub specie { return "unknow specie"; } ... #Zoo/Animal/Camel.pm ... sub specie { return "cameloid Dromedarius" } # Main my $zoo=Zoo->new(); $zoo->adquire(Zoo::Animal::Camel->new(), Zoo::Animal::Camel->new()); %count=$zoo->count(); If you prefer you could yet implement the count as an hash, and increment it in the adquire Zoo method, like this: sub adquire { my $self=shift; for my $anim (@_) { $self->{count}->{$anim->specie()}++; push @{$self->{animals}}, $anim; } }	[reply]

Replies are listed 'Best First'.

Re: Re: Creating Common Constructor
by themage (Friar) on Jul 13, 2003 at 12:44 UTC

sub Zoo::factory {
  my ($self, $class, @args)=@_;

  my $obj="Zoo::Animal::$class"->new(@args);
  $self->{count}->{$class}++;

  return $obj;
}

my $zoo=Zoo->new();
my $camel=$zoo->factory("Camel");

#Zoo.pm file
sub new {
  ...
  $self->{animals}=[];
  ...
}

sub adquire {
  my $self=shift;
  push @{$self->{animals}}, @_;
}

sub count {
  my $self=shift;
  my %count=();
  for my $anim (@{$self->{animals}}) {
    $count{$anim->specie()}++;
  }
  return %count;
}

#Zoo/Animal.pm
...
sub specie {
  return "unknow specie";
}
...

#Zoo/Animal/Camel.pm
...
sub specie {
  return "cameloid Dromedarius"
}

# Main
my $zoo=Zoo->new();
$zoo->adquire(Zoo::Animal::Camel->new(), Zoo::Animal::Camel->new());
%count=$zoo->count();

sub adquire {
  my $self=shift;
  for my $anim (@_) {
    $self->{count}->{$anim->specie()}++;
    push @{$self->{animals}}, $anim;
  }
}

[reply]