From: Christian Neukirchen <chneukirchen@...>
Date: 2005-09-20T21:22:16+09:00
Subject: [ANN] Dissident 0.1, a Ruby dependency injection container

Hello,

Although it took a bit longer than I thought at first, I'm proud to
announce the first public release of Dissident, a Ruby dependency
injection container written by me.

== What does Dissident do?

Dissident tries to make the best of different kinds of dependency
injection:

* It is as unobtrusive as Setter Injection (aka Type II), but done
  magically.  It should feel exactly the same as just using the class
  if used properly.

* It is as easy as Constructor Injection (aka Type III) with, say,
  PicoContainer (or what it would look like in an dynamically typed
  language), but not as clumsy if used without DI.

* It is lazy, like Getter Injection (aka Type "IV"), and exactly as
  nice to use.  The laziness also solves the problem of circular
  instantiations in a clever way.

Dissident can provide real Constructor injection too, making the
classes truly independent of Dissident.

== Features

Dissident provides per-container "singletons" (multitons, actually, if
you make use of parameterized services), that are not globally unique
and visible everywhere to the program, but only for the scope of the
container used.

Dissident can do easy customization and "forking" of container
implementations using standard Ruby inheritance and overriding.  You
can, for example, inherit from your default container to add stubs for
testing.

Dissident provides multitons and multimethods for complete
configurability of your applications.  A prototypish instantiation
style exists too.

Dissident includes an extensive test suite and is implemented using
test-driven development.

The Dissident core is just a single and rather short file, ready to be
included in your application.  It has no external dependencies.

== Example code

An example of using Dissident:

    require 'dissident'

    class Apple
      def peel; end
    end

    class Peeler
      inject :peelable
      def start
        peelable.peel
      end
      def stop; end
    end

    class Juicer
      inject :peeler
      inject :peelable
    end

    class MyContainer < Dissident::Container
      provide :peeler, Peeler
      provide :peelable, Apple
    end

    Dissident.with MyContainer do
      juicer = Juicer.new
    end

== Warning

This release is meant to be thread-safe, but testing in this area has
not been very extensive.  Users of threaded applications beware and
please report bugs.

== License

Copyright (C) 2005  Christian Neukirchen <http://purl.org/net/chneukirchen>
Dissident is available under the same liberal terms as Ruby itself.

== Where can I get it?

You can get Dissident 0.1 at:

       http://chneukirchen.org/releases/dissident-0.1.0.tar.gz

Alternatively, you can checkout from the development repository with:

	  darcs get http://chneukirchen.org/repos/dissident

(Patches using "darcs send" are most welcome.)

For more information on Dissident, please also see
http://rubyurl.com/bPh and http://rubyurl.com/PMc

Quoting from the latter:

> But why write a new DI framework at all? There are some prejudices
> in the Ruby community with respect to that. People say "they make
> things complicated" and "there are more frameworks than users". Of
> course, that may be true---but it shouldn't be for all of
> them. Therefore, I decided to make one that's not complicated,
> because you barely notice using it, one that's easy to pickup,
> because you can learn it in an afternoon and only need to write a
> few additional lines of Ruby---no XML or YAML needed, one that
> actually helps coding, because else it's a hobble and therefore no
> fun, one that eases testing, because you can mock the services
> easily (don't use a container at all, or simply inject mocks), one
> that feels like Ruby, because you should never tangle in bad ports
> of Java libraries; in the end, I decided to make one that I
> personally like and want to use, because there is no point in making
> libraries you don't use on your own.


Happy hacking and have a nice day,
Christian Neukirchen

ea5772084443719e310f586ff43436e2  dissident-0.1.0.tar.gz
-- 
Christian Neukirchen  <chneukirchen@gmail.com>  http://chneukirchen.org