For this week’s meeting, there will be two mini-presentations on F-Script and view-based animations in Core Animation. Source code and sample apps will be available afterwards. Read more…

Thanks to the support of the good folks at the Mac Developer Network, the NSConference talk on F-Script 2.0 is now available for free. The session explores the need for interactive manipulation of objects and shows some of the cool graphical tools provided by F-Script to achieve it. Other new features in F-Script 2 are discussed, including dynamic Cocoa class creation, system wide scripting and the latest in exploring applications from the inside through run-time injection.

If you have never used F-Script and want to know what it is all about, this video should provide you with a good overview, packed with demos of interesting dynamic object-oriented technologies. If you are a regular F-Script user, you’ll feel at home but might still learn a few neat tricks.

You can watch the embedded video above or get to the video on its Vimeo page.

The main new feature in this version is support for adding methods to existing classes. This is similar to Objective-C categories, but works dynamically at run-time. This is quite useful for prototyping stuff and experimenting with new designs, as well as for making object-oriented frameworks developed independently work together. Besides, it is a natural extension of the ability to define Cocoa classes directly in F-Script and lets you write a bigger part of your application code in F-Script, should you want to.

You can teach new tricks to any class registered in the Objective-C runtime, regardless of its original implementation language (Objective-C, F-Script or other). The syntax is straightforward: class name followed by new methods inside a pair of curly braces. For example, here is how we can add a print method the NSObject class:

NSObject
{
   - (void)print
   {
       "Print the receiver's description on standard output."
       stdout print:self description
   }
}

Of course, this also works for class methods. For example, the following code adds a pi method to the NSNumber class:

NSNumber
{
   + pi
   {
       ^ 3.141592653589793
   }
}

The following example, a little bit more sophisticated, adds some common Smalltalk collection methods (namely collect:, inject:into:, groupedBy: and select:) to the NSArray class:

NSArray
{
   - collect:transformer
   {
       "Answer a new NSArray constructed by gathering the results of
        evaluating transformer (a block with one parameter) with each
        element of the receiver."

       ^ transformer value:@self
   }

   - groupedBy:criteria
   {
       "Answer an NSDictionary whose keys are the result of evaluating
        criteria (a block with one parameter) for all elements in the
        collection, and the value for each key is the collection of
        elements that evaluated to that key. For example
          {'Hello', 'guys', 'I', 'enjoy', 'programming', 'with', 'style'}
          groupedBy:#length
        returns a dictionary with the following key/value associations:
           1 -> {'I'},
           4 -> {'guys', 'with'},
           5 -> {'hello', 'enjoy', 'style'},
          11 -> {'programming'}"

       | result |
       result := #{}.

       self do:[:each|
           | key group |
           key := criteria value:each.
           group := result at:key.
           group == nil ifTrue:
           [
               group := {}.
               result at:key put:group.
           ].
           group addObject:each.
       ].

       ^ result
   }

   - inject:initialValue into:operation
   {
       "Answer the final result of evaluating operation (a block with
        two parameters) using the previous evaluation result and each
        element of the receiver as the parameters. The first evaluation
        of operation is performed with initialValue as the first
        parameter, and the first element of the receiver as the second
        parameter. For instance, to sum the numeric elements of an
        array, use:
            anArray inject:0 into:#+"

       | nextValue |
       nextValue := initialValue.
       self do:[:each|
           nextValue := operation value:nextValue value:each
       ].
       ^ nextValue
   }

   - select:discriminator
   {
       "Answer a new NSArray which contains the elements in the
        receiver which cause discriminator (a block with one parameter)
        to evaluate to true. For each element of the receiver,
        discriminator is evaluated with the element as the parameter.
        Each element which causes discriminator to evaluate to true is
        added to the new array."

       ^ self where:(discriminator value:@self)
   }
}

Share and enjoy!

There are many ways to think through the flow of a program, and times when certain constructs like switch statements are a nice option, even in a language with no syntactical support for it, per se. Philippe Mougin was discussing just such options in F-Script back in the Oughts. I had a need for switching in F-Script, and came up with a few versions that I found useful. Read more…

With this book, Pejvan comes back to its Cocoa roots. A number of french developers will remember him, as he has been very active in the early years of Mac OS X both as a member of Apple Developer Relations and as a founder of the Cocoa enthusiasts community Project:Omega (incidentally, he was the french translator for the original O’Reilly F-Script articles series). In the book, he makes approaching Objective-C 2.0 easier for people coming from other languages by often comparing its syntax and functionalities to those of Java and C# (with a little bit of Python too). He also puts emphasis on code quality, with advices on dealing with errors, assertions and unit tests.

Since the dawn of times, F-Script injection was provided by F-Script Anywhere. But as you may know, Snow Leopard broke it without mercy. Fortunately, an alternative F-Script injection mechanism has been made available. Still, it requires launching gdb and typing a command, which is boring.

Today, I'm glad to announce that all of this is now entirely automated, thanks to the injection service developed by Silvio H. Ferreira. It adds an automated F-Script injection procedure in the Services menu, meaning that injecting a whole F-Script environment in an application is now just two mouse clicks away: one to go to the Services menu, and one to select the "Inject F-Script into application" item. This brings back the zero configuration and ease of use spirit of good old F-Script Anywhere.

Picture: injecting F-Script into the Finder using the new injection service

Once injected (which can take a few seconds), F-Script will make itself available by adding an F-Script menu in the menu bar of the target application.

You can download the F-Script injection service here (for Mac OS X 10.6).

Enjoy!