objects

Perl Ruby PHP Python

スクリプト言語の比較

http://hyperpolyglot.org/scripting を参考に、スクリプト言語の勉強をしてまいります。

objects















































  perl php python ruby
define class 

package Int;
use Moose;
has 'value' => ( is => 'rw' );
around BUILDARGS => sub {
  my $orig = shift;
  my $class = shift;
  my $v = $_[0] || 0;
  $class->$orig(value => $v);
};
no Moose;


<?php
class Int {
  private $value;
  function __construct($int=0) {
    $this->value = $int;
  }
  function getValue() {
    return $this->value;
  }
  function setValue($i) {
    $this->value = $i;
  }
}
?>


class Int:
  def __init__(self, v=0):
    self.value = v


class Int
  attr_accessor :value
  def initialize(i=0)
    @value = i
  end
end

create object 

my $i = new Int(); # or
my $i = Int->new();


<?php
$i = new Int();
?>


i = Int()


i = Int.new

invoke getter, setter 

my $v = $i->value;
$i->value($v+1);


<?php
$v = $i->getValue();
$i->setValue($v+1);
?>


v = i.value
i.value = v+1


v = i.value
i.value = v+1

instance variable accessibility 


private by default
 


must be declared
 


public; attributes starting

with underscore private

by convention
 


private by default;

use attr_reader, 

attr_writer, 

attr_accessor

to make public
define method 

# in package:
sub plus {
  my $self = shift;
  $self->value + $_[0];
}


<?php
function plus($i) {
  return $this->value + $i;
}
?>


def plus(self,v):
  return self.value + v


def plus(i)
  value + i
end

invoke method 

$i->plus(7)


<?php
$i->plus(7)
?>


i.plus(7)


i.plus(7)

destructor 

# in package:
sub DEMOLISH {
  my $self = shift;
  my $v = $self->value;
  print "bye, $v\n";
}


<?php
function __destruct() {
  echo "bye, $this->value\n";
}
?>


def __del__(self):
  print("bye, %", self.value)


val = i.value
ObjectSpace.define_finalizer(int) {
  puts "bye, #{val}"
}

method missing 

# in package:
our $AUTOLOAD;
sub AUTOLOAD {
  my $self = shift;
  my $argc = scalar(@_);
  print "no def: $AUTOLOAD"
    . " arity: $argc\n";
}


<?php
function __call($name, $args) {
  $argc = count($args);
  echo "no def: $name " .
    "arity: $argc\n";
}
?>


def __getattr__(self, name):
  s = "no def: "+name+" arity: %d"
  return lambda *a: print(s % len(a))


def method_missing(name, *a)
  puts "no def: #{name}" +
    " arity: #{a.size}"
end

inheritance 

package Counter;
use Moose;
extends 'Int';
my $instances = 0;
sub BUILD {
  $instances += 1;
}
sub incr {
  my $self = shift;
  my $v = $self->value;
  $self->value($v + 1);
}
sub instances {
  $instances;
}
no Moose;


<?php
class Counter extends Int {
  private static $instances = 0;
  function __construct($int=0) {
    Counter::$instances += 1;
    parent::__construct($int);
  }
  function incr() {
    $i = $this->getValue();
    $this->setValue($i+1);
  }
  static function getInstances() {
    return $instances;
  }
}
?>


class Counter(Int):
  instances = 0
  def __init__(self, v=0):
    Counter.instances += 1
    Int.__init__(self, v)
  def incr(self):
    self.value += 1


class Counter < Int
  @@instances = 0
  def initialize
    @@instances += 1
    super
  end
  def incr
    self.value += 1
  end
  def self.instances
    @@instances
  end
end

invoke class method 

Counter::instances();


<?php
Counter::getInstances()
?>


Counter.instances


Counter.instances

スクリプト言語の比較 - 目次

main page
arithmetic and logic
strings
containers
functions
execution control
environment and i/o
libraries and modules
objects
reflection and hooks