bar.rb

# 基底クラス
class Payment
  def payment_class(payment_type)
    "#{payment_type}Payment"
  end
  
  def pay(payment_type)
    Object.const_get(payment_class payment_type).new.commit
  end
end
 
# 具象クラス
class CardPayment < Payment
  def commit
    puts "card"
  end
end
 
class ConveniPayment < Payment
  def commit
    puts "conveni"
  end
end
 
# 呼び出す側
class Order
  def pay(payment_method)
    Payment.new.pay payment_method
  end
end
 
Order.new.pay('Card') # => CardPayment.commit
Order.new.pay('Conveni') # => ConveniPayment.commit

barbar.rb

# 基底クラス
class Payment
  def payment_class(payment_type)
    "#{payment_type}Payment"
  end
  
  def pay(payment_type, order)
    Object.const_get(payment_class payment_type).new.commit order
  end
end
 
# 具象クラス
class CardPayment < Payment
  def commit(order)
    call_api order.card_attributes
  end
  
  def call_api
    # カード決済のAPI叩く
  end
end
 
class ConveniPayment < Payment
  def commit(order)
    call_api order.conveni_attributes
  end
  
  def call_api
    # コンビニ決済のAPI叩く
  end
end
 
# 呼び出す側
class Order
  def pay(payment_method)
    Payment.new.pay(payment_method, self)
  end
  
  def card_attributes
    # クレジットカードの決済APIを叩く用の引数
  end
  
  def conveni_attributes
    # コンビニの決済APIを叩く用の引数
  end
end
 
Order.new.pay('Card') # => CardPayment.commit
Order.new.pay('Conveni') # => ConveniPayment.commit

baz.php

<?php

class Payment
{
  public static function new_instance($payment_type)
  {
    return new sprintf('%sPayment', $payment_type);
  }

  public function pay()
  {
    $this->commit();
  }

  abstract protected function commit();
}

class CardPayment extends Payment
{
  protected function commit()
  {
  }
}

class ConveniPayment extends Payment
{
  protected function commit()
  {
  }
}

Payment::new_instance('Card')->pay();
Payment::new_instance('Conveni')->pay();

foo.rb

# 基底クラス
class Payment
  def self.commit
  end
end

# 具象クラス
class CardPayment < Payment
end

class ConveniPayment < Payment
end

# 呼び出す側
class Order
  def pay(payment_type)
    "#{payment_type}Payment".constantize.commit
  end
end

Order.new.pay('Card') # => CardPayment.commit
Order.new.pay('Conveni') # => ConveniPayment.commit

<?php

class Payment
{
  public static function new_instance($payment_type)
  {
    return new sprintf('%sPayment', $payment_type);
  }

  public function pay()
  {
    $this->commit();
  }

  abstract protected function commit();
}

class CardPayment extends Payment
{
  protected function commit()
  {
  }
}

class ConveniPayment extends Payment
{
  protected function commit()
  {
  }
}

Payment::new_instance('Card')->pay();
Payment::new_instance('Conveni')->pay();