/en/about/index.md

---
layout: page
title: "About Ruby"
lang: en
---

Wondering why Ruby is so popular? Its fans call it a beautiful, artful
language. And yet, they say it’s handy and practical. What gives?
{: .summary}

### The Ideals of Ruby’s Creator

Ruby is a language of careful balance. Its creator, [Yukihiro “Matz”
Matsumoto][matz], blended parts of his favorite languages (Perl, Smalltalk,
Eiffel, Ada, and Lisp) to form a new language that balanced functional
programming with imperative programming.

He has often said that he is “trying to make Ruby natural, not simple,”
in a way that mirrors life.

Building on this, he adds:

> Ruby is simple in appearance, but is very complex inside, just like
> our human body<sup>[1](#fn1)</sup>.

### About Ruby’s Growth

Since its public release in 1995, Ruby has drawn devoted coders
worldwide. In 2006, Ruby achieved mass acceptance. With active user
groups formed in the world’s major cities and Ruby-related conferences
filled to capacity.

![Graph courtesy of
Gmane.](http://gmane.org/plot-rate.php?group=gmane.comp.lang.ruby.general&amp;width=320&amp;height=160&amp;title=Ruby-Talk+Activity
"Graph courtesy of Gmane."){: style="padding-left:8px;"}
{: style="float:right"}

Ruby-Talk, the primary [mailing list](/en/community/mailing-lists/) for
discussion of the Ruby language, climbed to an average of 200 messages
per day in 2006. It has dropped in recent years as the size of the
community pushed discussion from one central list into many smaller
groups.

Ruby is ranked among the top 10 on most of the indices that measure
the growth and popularity of programming languages worldwide
(such as the [TIOBE index][tiobe]). Much of the growth is attributed to the
popularity of software written in Ruby, particularly the
[Ruby on Rails][ror] web framework.

Ruby is also [completely free]({{ site.license.url }}). Not only free of charge, but
also free to use, copy, modify, and distribute.

### Seeing Everything as an Object

Initially, Matz looked at other languages to find an ideal syntax.
Recalling his search, he said, “I wanted a scripting language that was
more powerful than Perl, and more object-oriented than
Python<sup>[2](#fn2)</sup>.”

In Ruby, everything is an object. Every bit of information and code can
be given their own properties and actions. Object-oriented programming
calls properties by the name *instance variables* and actions are known
as *methods*. Ruby’s pure object-oriented approach is most commonly
demonstrated by a bit of code which applies an action to a number.

{% highlight ruby %}
5.times { print "We *love* Ruby -- it's outrageous!" }
{% endhighlight %}

In many languages, numbers and other primitive types are not objects.
Ruby follows the influence of the Smalltalk language by giving methods
and instance variables to all of its types. This eases one’s use of
Ruby, since rules applying to objects apply to all of Ruby.

### Ruby’s Flexibility

Ruby is seen as a flexible language, since it allows its users to freely
alter its parts. Essential parts of Ruby can be removed or redefined, at
will. Existing parts can be added upon. Ruby tries not to restrict the
coder.

For example, addition is performed with the plus (`+`) operator. But, if
you’d rather use the readable word `plus`, you could add such a method
to Ruby’s builtin `Numeric` class.

{% highlight ruby %}
class Numeric
  def plus(x)
    self.+(x)
  end
end

y = 5.plus 6
# y is now equal to 11
{% endhighlight %}

Ruby’s operators are syntactic sugar for methods. You can redefine them
as well.

### Blocks: a Truly Expressive Feature

Ruby’s block are also seen as a source of great flexibility. A
programmer can attach a closure to any method, describing how that
method should act. The closure is called a *block* and has become one of
the most popular features for newcomers to Ruby from other imperative
languages like PHP or Visual Basic.

Blocks are inspired by functional languages. Matz said, “in Ruby
closures, I wanted to respect the Lisp culture<sup>[3](#fn3)</sup>.”

{% highlight ruby %}
search_engines =
  %w[Google Yahoo MSN].map do |engine|
    "http://www." + engine.downcase + ".com"
  end
{% endhighlight %}

In the above code, the block is described inside the `do ... end`
construct. The `map` method applies the block to the provided list of
words. Many other methods in Ruby leave a hole open for a coder to write
their own block to fill in the details of what that method should do.

### Ruby and the Mixin

Unlike many object-oriented languages, Ruby features single inheritance
only, **on purpose**. But Ruby knows the concept of modules (called
Categories in Objective-C). Modules are collections of methods.

Classes can mixin a module and receive all its methods for free. For
example, any class which implements the `each` method can mixin the
`Enumerable` module, which adds a pile of methods that use `each` for
looping.

{% highlight ruby %}
class MyArray
  include Enumerable
end
{% endhighlight %}

Generally, Rubyists see this as a much clearer way than multiple
inheritance, which is complex and can be too restrictive.

### Ruby’s Visual Appearance

While Ruby often uses very limited punctuation and usually prefers
English keywords, some punctuation is used to decorate Ruby. Ruby needs
no variable declarations. It uses simple naming conventions to denote
the scope of variables.

* `var` could be a local variable.
* `@var` is an instance variable.
* `$var` is a global variable.

These sigils enhance readability by allowing the programmer to easily
identify the roles of each variable. It also becomes unnecessary to use
a tiresome `self.` prepended to every instance member.

### Beyond the Basics

Ruby has a wealth of other features, among which are the following:

* Ruby has exception handling features, like Java or Python, to make it
  easy to handle errors.

* Ruby features a true mark-and-sweep garbage collector for all Ruby
  objects. No need to maintain reference counts in extension libraries.
  As Matz says, “This is better for your health.”

* Writing C extensions in Ruby is easier than in Perl or Python, with a
  very elegant API for calling Ruby from C. This includes calls for
  embedding Ruby in software, for use as a scripting language. A SWIG
  interface is also available.

* Ruby can load extension libraries dynamically if an OS allows.

* Ruby features OS independent threading. Thus, for all platforms on
  which Ruby runs, you also have multithreading, regardless of if the OS
  supports it or not, even on MS-DOS!

* Ruby is highly portable: it is developed mostly on GNU/Linux, but
  works on many types of UNIX, Mac OS X, Windows 95/98/Me/NT/2000/XP,
  DOS, BeOS, OS/2, etc.

### Other Implementations of Ruby

Ruby, as a language, has a few different implementations.
This page has been discussing the reference implementation, in the
community often referred to as **MRI** (“Matz’s Ruby Interpreter”)
or **CRuby** (since it is written in C), but there are also others.
They are often useful in certain situations, provide extra
integration to other languages or environments, or have special features
that MRI doesn’t.

Here’s a list:

* [JRuby][jruby] is Ruby atop the JVM (Java Virtual Machine), utilizing the
  JVM’s optimizing JIT compilers, garbage collectors, concurrent
  threads, tool ecosystem, and vast collection of libraries.
* [Rubinius][rubinius] is ‘Ruby written in Ruby’. Built on top of LLVM,
  Rubinius sports a nifty virtual machine that other languages are being
  built on top of, too.
* [MacRuby][macruby] is a Ruby that’s tightly integrated with Apple’s Cocoa
  libraries for Mac OS X, allowing you to write desktop applications
  with ease.
* [mruby][mruby] is a lightweight implementation of the Ruby language
  that can be linked and embedded within an application.
  Its development is led by Ruby’s creator Yukihiro “Matz” Matsumoto.
* [IronRuby][ironruby] is an implementation “tightly integrated with the .NET
  Framework”.
* [MagLev][maglev] is “a fast, stable, Ruby implementation with integrated
  object persistence and distributed shared cache”.
* [Cardinal][cardinal] is a “Ruby compiler for [Parrot][parrot] Virtual Machine”
  (Perl 6).

Some of those implementations, including MRI, follow the guidelines of
[RubySpec][rubyspec], a “complete executable specification for the Ruby
programming language”.

### References

<sup>1</sup> Matz, speaking on the Ruby-Talk mailing list, [May 12th,
2000][blade].
{: #fn1}

<sup>2</sup> Matz, in [An Interview with the Creator of Ruby][linuxdevcenter], Nov.
29th, 2001.
{: #fn2}

<sup>3</sup> Matz, in [Blocks and Closures in Ruby][artima], December 22nd,
2003.
{: #fn3}



[matz]: http://www.rubyist.net/~matz/
[blade]: http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/2773
[ror]: http://rubyonrails.org/
[linuxdevcenter]: http://www.linuxdevcenter.com/pub/a/linux/2001/11/29/ruby.html
[artima]: http://www.artima.com/intv/closures2.html
[tiobe]: http://www.tiobe.com/index.php/content/paperinfo/tpci/index.html
[jruby]: http://jruby.org
[rubinius]: http://rubini.us
[macruby]: http://www.macruby.org
[mruby]: http://www.mruby.org/
[ironruby]: http://www.ironruby.net
[maglev]: http://ruby.gemstone.com
[cardinal]: https://github.com/parrot/cardinal
[parrot]: http://parrot.org
[rubyspec]: http://rubyspec.org