Editing RubyCocoa

{{Short description|MacOS framework}}
{{Portal|Free and open-source software}}{{More sources|date=December 2024}}
'''RubyCocoa''' is a [[macOS]] [[Software framework|framework]] that provides a bridge between the [[Ruby (programming language)|Ruby]] and the [[Objective-C]] programming languages, allowing the user to manipulate Objective-C [[object (computer science)|object]]s from Ruby, and vice versa. It makes it possible to write a [[Cocoa (API)|Cocoa]] application completely in Ruby as well as to write an application that mixes Ruby and Objective-C code.<ref name=":0">{{Cite web |title=File: RubyCocoa - A Ruby/Objective-C Bridge — RubyCocoa Documentation |url=https://rubycocoa.github.io/ |access-date=2024-12-18 |website=rubycocoa.github.io}}</ref> An Apple project called [[MacRuby]] was under development to replace RubyCocoa in 2008.<ref>{{Cite web |date=2010-04-02 |title=Pragmatic Forums {{!}} Does MacRuby change the game? |url=http://forums.pragprog.com/forums/76/topics/687#posts-4160 |access-date=2024-12-18 |archive-url=https://web.archive.org/web/20100402104046/http://forums.pragprog.com/forums/76/topics/687#posts-4160 |archive-date=2 April 2010 }}</ref> A proprietary spin-off called [[RubyMotion]] was subsequently released in 2012, available for iOS, macOS and Android.<ref>{{Cite web |title=About RubyMotion {{!}} RubyMotion |url=http://www.rubymotion.com/about/ |access-date=2024-12-18 |website=rubymotion.com}}</ref>

RubyCocoa is used for exploration of a Cocoa object's features with [[Interactive Ruby Shell|irb]] interactively, prototyping of a Cocoa application, writing a Cocoa application that combines the features of Ruby and Objective-C, and wrapping macOS' native [[GUI]] for a Ruby script.<ref>{{Cite web |title=Ruby and Python on OS X |url=https://developer.apple.com/library/archive/documentation/Cocoa/Conceptual/RubyPythonCocoa/Articles/RubyPythonMacOSX.html#//apple_ref/doc/uid/TP40005423-SW7 |access-date=2024-12-18 |website=developer.apple.com}}</ref>

RubyCocoa is [[free software]], released under both the [[Ruby License]] and the [[LGPL]].<ref name=":0" />

== History ==
RubyCocoa was started in 2001 by Hisakuni Fujimoto when he implemented a Ruby extension module to wrap NSObject and NSClassFromString function. Later it was integrated with Project Builder (which later became [[Xcode]]). In 2002 the project was registered on SourceForge and the development team began to grow.

In 2006 the committers list was first joined by a developer from [[Apple Inc.|Apple]], Laurent Sansonetti, and then a RubyCocoa presentation was made during [[WWDC]]. Apple stated that RubyCocoa will be included and supported in [[Mac OS X v10.5]] “Leopard”.

In August 2008, Sansonetti confirmed that [[MacRuby]] "is supposed to replace RubyCocoa." in the future.<ref>{{Cite web |title=Pragmatic Bookshelf: By Developers, For Developers |url=https://pragprog.com |access-date=2024-12-18 |website=pragprog.com}}</ref>

== Functionality ==
RubyCocoa is sometimes interpreted as a set of bindings to the Cocoa frameworks, which is false. RubyCocoa is a real bridge between the Objective-C and Ruby programming languages.

=== Lazy class import ===
RubyCocoa will import the Objective-C classes into the Ruby world on demand. For example, when you access <code>OSX::NSTableView</code> for the very first time in your code, RubyCocoa will retrieve all the necessary information regarding this class from the Objective-C runtime and create a Ruby class of the same name that will act as a proxy. It will also import in the same way all the inherited classes.

=== Forwarding messages ===
Every time the user sends a Ruby message to a proxy object, RubyCocoa will try to forward it to the embedded Objective-C instance, by translating the message name to an Objective-C selector and asking the Objective-C runtime to forward it.

If an exception is raised from the Objective-C world, RubyCocoa will convert it to a Ruby exception and forward it to you.

RubyCocoa uses the [[libffi]] library to call the Objective-C methods implementations.

=== Automatic method overriding ===
RubyCocoa makes it easy to override an Objective-C method from Ruby, either in a subclass or directly to the class (as you would do in Objective-C using a category).

Once your method is inserted, RubyCocoa will retrieve the signature of the existing Objective-C method and inject a new one to the Objective-C runtime, of the same signature, but which now points to your code.

To accomplish this, RubyCocoa uses the [[libffi]] library to dynamically create a closure that will call the Ruby method, and just passes a pointer to that new closure to the Objective-C runtime.

=== Accessing the C bits ===
Due to the nature of the Objective-C language, you can freely use [[C (programming language)|C]] from Objective-C code. In order to bridge the relevant C parts of an Objective-C framework, such as C structures, functions, enumerations, constants and more, RubyCocoa relies on the [[BridgeSupport]] project.

RubyCocoa will interpret at runtime the BridgeSupport files (using the very fast [[libXML]]2's xmlTextReader) and accordingly handle their content. It will for instance construct the Ruby proxy classes for the C structures and also create the functions.

Note that the costly operations, such as localizing the symbols, are done on demand, and obviously only once.

=== Format strings ===
RubyCocoa is able to detect APIs that use format strings, like NSLog or NSString.stringWithFormat, and appropriately convert the variable arguments to the types specified in the format string.

=== Function pointers ===
RubyCocoa allows you to pass Ruby <code>Proc</code> objects as function pointer arguments. It will then use the [[libffi]] library to dynamically create a closure and pass it to the underlying function/method.

== Creation of Cocoa applications written in Ruby ==

Installing RubyCocoa also automatically installs the corresponding [[Xcode]] templates. This allows developers to select "Cocoa-Ruby Application" as the Xcode project type and Xcode will generate all necessary files for them.
== How to call Objective-C methods from Ruby ==
To invoke an Objective-C method, you replace each colon in the method name except the last with an underscore. Thus, for example, the NSWindow instance method <code>initWithContentRect:styleMask:backing:defer:</code> becomes <code>initWithContentRect_styleMask_backing_defer</code>.

All Cocoa classes and functions belong to <code>OSX</code> module, so for example, the Objective-C code:

<syntaxhighlight lang="objc">
[[NSWindow alloc] initWithContentRect:frame
                            styleMask:NSTitledWindowMask
                              backing:NSBackingStoreBuffered
                                defer:NO]
</syntaxhighlight>

will become:

<syntaxhighlight lang="ruby">
OSX::NSWindow.alloc.initWithContentRect_styleMask_backing_defer(frame,
  OSX::NSTitledWindowMask,
  OSX::NSBackingStoreBuffered,
  false)
</syntaxhighlight>

As you can see, this decreases the code readability by rendering Objective-C parameter naming useless. So, there is another convenient way to write the method calls — the <code>objc_send</code> method, which accepts Ruby symbols as parameter names. For example, the previous code can also be written as:

<syntaxhighlight lang="ruby">
OSX::NSWindow.alloc.objc_send(:initWithContentRect, frame,
  :styleMask, OSX::NSTitledWindowMask,
  :backing, OSX::NSBackingStoreBuffered,
  :defer, false)
</syntaxhighlight>

== Advantages of RubyCocoa ==
* As Ruby is an interpreted language, there's no need to recompile the application frequently during development.
* Some of Ruby's rich features, like built-in [[regular expression]] support, make writing the code faster, and also make RubyCocoa an ideal tool for prototyping.

== Disadvantages ==
* Ignoring the speed of the Ruby interpreter, RubyCocoa applications will always be slower than Objective-C/Cocoa applications due to the added overhead of object conversion.
* Because Ruby isn't thread-safe, it isn't possible to dispatch multiple native threads to execute RubyCocoa code. Ruby's emulated threads, however, can be used.

==References==
{{reflist}}

==External links==
* [http://sourceforge.net/projects/rubycocoa/ RubyCocoa page on SourceForge]

{{Ruby programming language}}

[[Category:MacOS programming tools]]
[[Category:Ruby (programming language)]]