Ruby meets Cocoa
Eloy Duran

Online
http://superalloy.nl/slides/ruby_meets_cocoa.pdf

Who is this guy?!
class EloyDuran < HomoSapiensObject
attr_reader http://superalloy.nl/blog
attr_writer e.duran@superalloy.nl
def self.rubycocoa_os_stuff
{ :qtkit => 'Back in the day, when it was impossible to access C functions provided with a
framework from the Ruby side of the RubyCocoa bridge. I had written a wrapper
for QTKit which implemented all those functions.',
:bridge_doc => 'A tool that ships with RubyCocoa which parses the Apple Objective-C
HTML reference files and transforms the Objective-C methods to the way
that calling is done from Ruby. The outputted ruby source files are then
passed to rdoc which creates HTML and ri documentation.',
:ActiveRecordBindingsSupport => 'A set of Cocoa subclasses, included with RubyCocoa,
which try to be the glue between Cocoa Bindings and
ActiveRecord. Allowing you to create a CoreData like
application, but instead using ActiveRecord as a backend.' }
end
def self.recent_super_secret_commercial_project
\"Can't say much about it, but basically it's a platform consisting of a server and clients,
which handle the distribution of media files used in narrowcasting. The server is a Rails
application with a Flex frontend to add media files to playlists. The clients are mac mini's
that communicate with the server to see what they need to display and then start the transfer
via the bittorrent protocol. The clients also run a application which displays the media
files when needed. This player is created with RubyCocoa.\"
end
end

What is this Cocoa thing?
• Cocoa is Apple’s native object-orientated programming
environment for Mac OS X, written in Objective-C.
• It’s derived from the NeXTSTEP and OPENSTEP programming
environments developed by NeXT in the late 80’s.
This is still visible in the prefix of all the class names, which is the
acronym “NS” (for NeXTSTEP): NSString, NSArray etc.
• It is a collection of frameworks, most notably:
• Foundation Kit / Foundation: not tied to the GUI
eg: string manipulations.
• Application Kit / AppKit: to interact with the GUI
eg: buttons, text fields.

Objective-C
• Created by Brad Cox and Tom Love in the early 80’s,
influenced heavily by Smalltalk.
• Object-oriented programming language.
• A strict superset of C, which means that any C code can be
compiled by an Objective-C compiler.
• Most of the syntax is inherited from C, the object-orientated
syntax was added to allow Smalltalk-style messaging.
• Like C, lots of semi-colons....

Objective-C example
Let’s say we have an instance of a class,
which implements the following instance method:
// An instance method called sayMessage:toPerson:
- (void)sayMessage:(NSString)msg toPerson:(NSString)person
{
NSLog(@”%@ %@!”, msg, person);
}
When we pass the instance the sayMessage:toPerson message,
a line will be printed to the console by NSLog()
[theInstance sayMessage:@”Hello” toPerson:@”World”]; //=> “Hello World!”

The most important thing
about Objective-C to me....

I’m a total (Obj-)C noob!
by choice...

So, I need another solution
to make use of Cocoa’s
excellent facilities.

RubyCocoa

RubyCocoa History
• Late 2001: Started by Hisakuni Fujimoto. Release 0.1 - 0.4
• 2002 - 2006: Release 0.5. More committers joined:
Chris Thomas, Kimura Wataru, Jonathan Paisley, Tim Burks.
• 2006-05: Laurent Sansonetti (Apple inc) joins the committers list
in order to make RubyCocoa a first class citizen among the
programming languages supported in Mac OS X10.5 (leopard).
Most notable is the addition of Libffi/BridgeSupport.
• 2006-11: I joined the committers list to add BridgeDoc.
• 2006-12: First preview (0.9) of the Apple branch was released.
• 2007-01: Second preview (0.10) was released.
• 2007-05: Third preview (0.11) and now officially the current
stable release was released.

What is RubyCocoa?
• It is a real bridge between the Ruby & Objective-C programming
languages. Which means it isn’t limited to a predefined set of
Cocoa frameworks.
• It works by creating a Ruby proxy class for a Objective-C class.
The method calls are sent through the use of Libffi.
Which also allows us to call C functions even though they aren’t
methods on objects.
• The classes are imported lazily.
Meaning that RubyCocoa imports them only on demand.
• BridgeSupport allows RubyCocoa to bridge other parts of a
framework, like C structures, constants.
• Because it’s a real bridge, it works both ways. Thus you can mix
Ruby and Objective-C inside your app.

RubyCocoa example
Let’s say we have an instance of a Objective-C class,
which implements the following instance method:
// An instance method called sayMessage:toPerson:
- (void)sayMessage:(NSString)msg toPerson:(NSString)person
Ruby doesn’t have named parameters (yet?),
so the selectors have to be translated in a way that we can use it:
# Traditional syntax
theInstance.sayMessage_toPerson_('Hello', 'World')
# Lazy traditional syntax
theInstance.sayMessage_toPerson('Hello', 'World')
# Alternative syntax
theInstance.objc_send(:sayMessage, 'Hello',
:toPerson, 'World')

Time for some action!
The state of the art
MailDemo sample
Let’s all pray uncle Murphy won’t act upon his law.....
Or laugh, whichever you prefer.

Questions?

Readfood:
•Hisakuni Fujimoto: http://fobj.com/hisa/d
•Laurent Sansonetti: http://chopine.be/lrz/diary
•Me: http://superalloy.nl/blog
•RubyCocoa website/wiki: http://rubycocoa.sf.net
•Drop by in the irc channel (freenode): #ruby-osx
•MailingLists: http://rubycocoa.sf.net/GettingSupport
•RubyCocoa tutorials: http://rubycocoa.com
•Original MailDemo tutorial:
http://cocoadevcentral.com/articles/000080.php
•Unlimited coding inspiration: http://www.johnnyweb.fr