Interface coding by contract design and dependency injection

[PerfectDayToChaseTornados]

Hi All,

I am a Java developer of many years & just starting to get into Ruby (&
really enjoying it!). However I am used to 'coding by contract' using
interfaces. This is especially great when using dependency injection
(usually via Spring). It makes testing very easy, as 'mocks' can be written
simply & then plugged in. I know that there isn't an equvalent for an
interface in Ruby, but is there a pattern which would typically be used? I
was wondering whether to create Modules in place of my interfaces & provide
them with methods which throw Exceptions, thus forcing them to be overrriden
in the classes that include them? Also how does one manage dependency
injection in Ruby? Is there a good framework/library/pattern typically used
for this, or are there good 'Ruby reasons' not to use DI?

Many thanks

 

[cmdjackryan]

Thee third google result for "dependency injection" is ruby-specific.

For me, it's a German Wikipedia article on DI.

http://de.wikipedia.org/wiki/Dependency_Injection

- Phill

 

[Paulo Köch]

Did you mean http://onestepback.org/index.cgi/Tech/Ruby/=20
DependencyInjectionInRuby.rdoc ?

Paulo Jorge Duarte K=F6ch
(e-mail address removed)

 

[Olivier]

Hi,

I'm really new to dependency injection in general, but I hope I can help,=20
though. I am aware of two libraries for what you want to do. Copland, first=
,=20
is an Inversion of Control (IoC) container, based on the Hivemind IoC=20
container for java.
As you said, there is no interface in Ruby, so Interface based injection is=
=20
not supported. However, Type 2 IoC (Setter Injection) and type 3 IoC=20
(Constructor Injection) are supported.
The second is Needle, which is a Dependency Injection container. I don't kn=
ow=20
much about it, except it supports a Service Locator mechanism.

By the way, the documentations are great for both ! Read them both and make=
=20
your choice !

http://needle.rubyforge.org/
http://copland.rubyforge.org/

=2D-
Olivier Renaud

Le lundi 29 janvier 2007 19:45, PerfectDayToChaseTornados a =E9crit=A0:

 

[PerfectDayToChaseTornados]

Thanks Guys,

I'll check out Copland & Needle, anyone have any experience with either of
these with Rails?

 

[cmdjackryan]

Did you mean
http://onestepback.org/index.cgi/Tech/Ruby/DependencyInjectionInRuby.rdoc ?

Paulo Jorge Duarte Köch
(e-mail address removed)

That didn't show up for me. Google results are depending on which data
center you catch, so just saying "google, and result #X will be
relevant" is a questionable technique to answer a question.

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