From: Florian Frank <flori@...>
Date: 2005-02-22T07:51:54+09:00
Subject: Re: Constructor overloading???


On 21.02.2005, at 23:15, Sam Roberts wrote:
> Trying to program in one language like it is another language is
> special.

And using lots of constructors in Java loses a lot of its attraction, 
if you're approaching two-digit numbers. One of the reasons, why Bloch 
gives the advice to use static factory methods instead of constructors 
in his book "Effective Java", is that you can give names to them. It's 
quite difficult to remember more than half a dozen type signatures and 
their permutations.

It's nicer in Ruby, too:

class Rectangle
    def initialize(a = 0, b = 0)
       @a, @b = a, b
       @color = :white
    end

    attr_reader :a, :b
    attr_writer :color

    def self.with_color(a, b, color)
      obj = new(a, b)
      obj.color = color
      obj
    end

    def self.[](a, b)
      new(a, b)
    end
end

r = Rectangle.new
# => #<Rectangle:0x94048 @b=0, @a=0, @color=:white>
s = Rectangle[3, 4]
# => #<Rectangle:0x91924 @b=4, @a=3, @color=:white>
t = Rectangle.with_color(3, 4, :red)
# => #<Rectangle:0x6e9f8 @b=4, @a=3, @color=:red>

-- 
Florian Frank