From: Sebastian Hungerecker <sepp2k@...>
Date: 2007-12-03T23:29:18+09:00
Subject: Re: What are the differences between c++ and Ruby?

duddilla's wrote:
> And my other question is what are
> exact differences between C++ and Ruby? and Ruby and Java?

There are a lot of differences. Here are some that come to mind right away:

In ruby everthing is an object:
5.class #=> Integer
Integer.class #=> Class

Ruby has convenient introspection methods:
some_object.class # What's some_object's class?
some_object.respond_to?("meth") # Does some_object have the method "meth"
some_object.methods # Which methods does this object have
SomeClass.instance_methods # Which methods do instances of the class have
...

In ruby you can reopen classes:
5.double #=> Error: No such method
class Integer
  def double()
    self * 2
  end
end
5.double #=> 10

Ruby has dynamic typing:
x = 5
x.class #=> Integer
x = "lala"
x.class #=> String

Ruby has blocks and a lot of methods that make good use of them:
[1,2,3,4].map {|x| x+3} #=> [4,5,6,7]
[5,7,11,8].any? {|x| x>10} #=> true
[5,7,11,8].all? {|x| x>10} #=> false
5.times { puts "Hello world" } # Prints "Hello World" five times.

In ruby you can easily define methods dynamically:
class String
  (2..10).each do |i|
    define_method("print_#{i}_times") do
      i.times {puts self}
    end
  end
end
"hi".print_4_times # Prints "hi" 4 times

And a lot of other things.


HTH,
Sebastian
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