Griffon Tip: MVC Groups

Recently I've been doing some refactoring of PSICAT to make better use of Griffon's MVC Groups.  I like MVC Groups because they provide self-contained building blocks that you can re-use throughout your application.  Below are a few tips that might be useful to others:

Creating MVC Groups
MVC Groups are created with the 'griffon create-mvc ' command.  This creates the appropriate files in the griffon-app directory structure and registers the MVC Group in Application.groovy.

When you want to use the new MVC group in your application, you have two ways to instantiate it: createMVCGroup and buildMVCGroup.  Both methods instantiate the MVC group but differ in the ordering of parameters passed to them and in what they return:

1. List[model, view, controller] createMVCGroup(type, id, paramMap)
2. Map['model': model, 'view':view, 'controller':controller, ...] buildMVCGroup(paramMap, type, id)

So if I had created an MVC group: 'griffon create-mvc Diagram', I could instantiate it in my application with either:
def list = createMVCGroup('Diagram', 'diagram1', [:])
or
def map = buildMVCGroup([:], 'Diagram', 'diagram1')


I was initially a bit confused as to why the parameters map was moved to the first argument for buildMVCGroup but then I remembered that Groovy lets you pass named parameters to a method and collects them all as a map.  This allows some nice syntactic sugar when creating an MVC group:
def map = buildMVCGroup('Diagram', 'diagram1', name: 'The Diagram', format: 'jpeg')


The other nifty thing is that Griffon automagically sets parameters passed when creating an MVC group to properties on the model (if applicable).  In the example above, if I had a name and a format properties on my model, they would be set to the values I passed instead of me having to explicitly set them in mvcGroupInit.


Destroying MVC Groups
While probably not critical, it's good practice to dispose of your MVC groups when you're done working with them.  You can do this by calling destroyMVCGroup with the id you passed when creating the group.  I find myself using many short-lived MVC groups.  To ensure I disposed of things properly, I whipped up a little method that simplifies things:

def withMVC(String type, String id, Map params, Closure closure) {
    closure(buildMVCGroup(params, type, id))
    destroyMVCGroup(id)
}

NOTE: you could do the same trick of moving the map to the first argument if you wanted to be able to pass 'loose' named parameters to the method.

You would call it in your code like so:

withMVC('NewSectionDialog', 'newSection', [ project: model.project ]) { mvc ->
    def section = mvc.controller.show()
    if (section) { model.projectSections << section }
}

This creates the MVC group, hands it to the closure you pass, and then destroys the group when done.

MVC groups are a nice feature of Griffon that let you create re-usable building blocks within your application.  Hopefully this tip helps you use them more effectively.

Happy Birthday Griffon

Well it looks like I'm a bit late to the party as James, Jim, Guillaume, and Andres already beat me to it, but I'll say it anyways: Happy Birthday Griffon!  As birthdays are a natural time for reflection, I thought I'd look through my blog archives to find my first Griffon post.  Although not one of my most original titles, My First Griffon App debuted on September 17, 2008 marking me as a happy Griffon user since nearly the beginning.  Since then I've written several other Griffon apps and a few more blog posts about Griffon.

It's been fun watching not only the project develop but also the enthusiastic community spring up around it.  As Jim mentioned in his post, Griffon's presence at JavaOne this year was a major highlight.  The fact that the major IDEs are adding Griffon support and Griffon in Action is set to release this March shows that Griffon truly has arrived.

So congrats to everyone involved.  If you haven't tried Griffon yet, what are you waiting for?  The upcoming 0.2 release is shaping up to be the best yet!

Griffon Tip: Mac Look and Feel on Snow Leopard

If you upgraded your Mac to Snow Leopard recently, you may have noticed that your Griffon apps no longer look the same as they used to on Leopard.  Aside from a few color differences, the biggest giveaway will be that your app no longer uses the standard top menubar.  Fortunately there is a simple fix if you want to use the more native look and feel.  Change your griffon-app/lifecycle/Initialize.groovy file to include the 'mac' look and feel first:

import groovy.swing.SwingBuilder
import griffon.util.GriffonPlatformHelper

GriffonPlatformHelper.tweakForNativePlatform(app)
SwingBuilder.lookAndFeel('mac', 'nimbus', 'gtk', ['metal', [boldFonts: false]])

The crux of the problem is SwingBuilder tries various L&Fs in the order you specify them and stops when it finds one that works.  Nimbus is the L&F for Java 6 but previous versions of Mac OS X shipped with Java 5.  So SwingBuilder would try Nimbus and it would fail then it would try the Mac look and feel which would work.  Snow Leopard ships with Java 6 so when SwingBuilder tried Nimbus, it worked and it never tried to set the Mac L&F.

EDIT: This will be the default behavior in the upcoming Griffon 0.2 release.  So you will only need this fix if you have Griffon apps from pre-0.2 days.

Griffon Tip: Intercepting Window Closing Events

When building an editor of sorts, it is often useful to intercept the window closing event so that you can prompt the user to save if the editor has unsaved changes.  To do this in Griffon, we first need to change the defaultCloseOperation and define a windowClosing event handler on our application node in the view:

application(title:'Editor', size:[800,600], locationByPlatform: true,
    defaultCloseOperation: WindowConstants.DO_NOTHING_ON_CLOSE, 
    windowClosing: { evt -> 
        // check if the editor needs saving
    }) {
// the rest of your view code here
}

If we run our application now, we should notice that...the windowClosing event handler never runs.  Turns out that there's one more step--we need to tell Griffon that we want to explicitly handle shutting down the application.  We do this by setting autoShutdown=false in griffon-app/conf/Application.groovy Once this is set, we should notice that our windowClosing event handler runs.  Since Griffon is no longer responsible for automatically shutting down our application, we must make sure to call app.shutdown() somewhere in our closing logic or the user won't be able to exit the app.

Building your Griffon app with Gradle

In this post, I'm going to show how to build your Griffon apps with Gradle. Griffon already comes with a command line tool to build and interact with your app, so why would you want to do this? I can think of a few reasons:

• you have an existing Gradle build you want to integrate with
• you have a complex build or packaging scenario
• you want to take advantage of Gradle's dependency management for your app

Prerequisites

1. Griffon
2. Gradle

The build.gradle file

Below is a generic Gradle build file for Griffon applications. Either copy and paste the code below or download it and place it in a build.gradle in your Griffon application folder.

// standard configuration
project.captureStandardOutput(LogLevel.INFO)
configurations { compile }

// add additional repositories here if you need them
repositories {
    //mavenRepo(urls:'http://download.java.net/maven/2/')
    mavenCentral()
}

// add any dependencies you want downloaded as part of the bootstrap process
dependencies {
    //compile 'com.google.collections:google-collections:1.0-rc2'
}

// this should be run once for the project
createTask('bootstrap') << {
    // download any dependencies and put them in lib/
    configurations['compile']?.files?.findAll { it.absolutePath.indexOf('unspecified') < 0 }.each { dep ->
        ant.copy(toDir: new File('lib'), file: dep)
    }

    // try to install any plugins
    new File('application.properties').eachLine { line ->
        if (line.startsWith("plugins")) {
            def plugin = line[8..-1].split('=')
            griffon "install-plugin ${plugin[0]} ${plugin[1]}"
        }
    }
}

// mimic the tasks provided by the Java plugin
createTask('clean') << { griffon 'clean' }
createTask('compile') << { griffon 'compile' }
createTask('libs') << { griffon 'package' }
createTask('test') << { griffon 'test-app' }
createTask('dists') << { griffon 'prod package' }

// additional run-related tasks
createTask('run-app') << { griffon 'run-app' }
createTask('debug-app') << { griffon 'run-app -debug' }
createTask('run-webstart') << { griffon 'run-webstart' }
createTask('run-applet') << { griffon 'run-applet' }

// call out to the griffon command
def griffon(target) {
    if (System.getProperty("os.name").toLowerCase().startsWith("win")) {
        ant.exec(executable: 'griffon.bat', dir: projectDir, failonerror: true) {
            arg(value: target)
        }
    } else {
        ant.exec(executable: 'griffon', dir: projectDir, failonerror: true) {
            arg(value: target)
        }
    }
}

// if you want to use the gradle wrapper
createTask('wrapper', type: Wrapper).configure {
    gradleVersion = '0.7'
}

To verify that everything is working, let's try running our app from Gradle (substitute gradle.bat if you are on Windows):
gradle run-app

Your Griffon app should run. If it doesn't, try invoking the Gradle command with the '-i' flag:
gradle -i run-app
to see what the problem is.

Multi-project Builds

So far it may seem like "What's the point?" We could already run our Griffon app with the griffon command. Where Gradle really starts to shine is when you start wanting to perform complex builds, such as building multiple Griffon apps at once or integrating with an existing build.

Gradle has good support for multi-project builds. Assuming you are using a directory layout like this:

settings.gradle
griffonapp1/
    build.gradle
    ...
griffonapp2/
    build.gradle
    ...

Building these multiple Griffon apps is as simple as listing them in the settings.gradle file:

include 'griffonapp1', 'griffonapp2'

Similarly, integrating with an existing build should be as simple as adding the name of your Griffon app to your existing settings.gradle file.

Complex Build/Packaging Scenarios

Griffon offers several packaging options with the Installer plugin. Sometimes you need more flexibility. For my PSICAT build, I wanted to package two Griffon apps together in a specific directory structure. The nice thing about Gradle build files is that they are just Groovy code and offer great integration with Ant. Below is a snippet from the PSICAT build that illustrates using Ant within Gradle:

// griffon create-all-launchers for PSICAT and SchemeEditor
griffon(psicat, 'create-all-launchers')
griffon(schemeEditor, 'create-all-launchers')

// build linux package
ant.copy(toDir: new File(linux, 'PSICAT')) {
    fileset(dir: new File(psicat, 'installer/linux/dist')) {
        include(name: 'bin/**')
        include(name: 'lib/**')
    }
}
ant.copy(toDir: new File(linux, 'PSICAT/tools/SchemeEditor')) {
    fileset(dir: new File(schemeEditor, 'installer/linux/dist')) {
        include(name: 'bin/**')
        include(name: 'lib/**')
    }
}
ant.chmod(perm: "+x", dir: new File(linux, 'PSICAT/bin'), includes: '*')
ant.chmod(perm: "+x", dir: new File(linux, 'PSICAT/tools/SchemeEditor/bin'), includes: '*')
ant.tar(destFile: new File(linux, "PSICAT-linux-${version}.tar.gz"), compression: 'gzip', basedir: linux, includes: 'PSICAT/**')
...

(if you're curious, the whole build.gradle file is here)

Cool Gradle Tricks

One cool feature of Gradle is that you can generate a 'wrapper' script that will download and bootstrap Gradle itself so that developers who download your source don't have to have Gradle installed to build your project.

The build.gradle file above is already setup to create this wrapper. You simply have to run the command:

gradle wrapper

and it will create four files in your project:

gradle-wrapper.jar
gradle-wrapper.properties
gradlew
gradlew.bat

If you include these files when you send someone your project, they can use the gradlew or gradlew.bat scripts as if they had Gradle installed:

./gradlew run-app

The other neat trick with Gradle is you can use its ability to pull from Maven repositories to bootstrap the dependencies of your Griffon app. This means you don't need to send someone your Griffon app with a bunch of JARs in the lib directory. Instead you can send them a Gradle-ized version of your app and tell them to run the command:

./gradlew bootstrap

This will download all of the dependencies you've listed in the build.gradle file and put them in the lib directory of your Griffon app. Specifying dependencies is as simple as adding a few lines to the dependencies section of the build file:

dependencies {
    compile 'com.google.collections:google-collections:1.0-rc2'
    compile 'org.slf4j:slf4j-api:1.5.8'
}

Conclusion

Hopefully this has given you a taste of using Gradle with Griffon. Both are awesome tools that really show off the power of the Groovy language. If there's enough interest in using Gradle with Griffon, we can make build.gradle a standard artifact created by the griffon create-app task.

Are Groovy Stacktraces a Showstopper?

I've been part of an interesting debate on the merits of Groovy via Twitter this week. I'm reproducing it here because I think it's an interesting take on what potential users feel are make or break issues for a language, and to give others who may not have seen it the chance to weigh in without the 140 character limit. :)

(Sorry in advance. Reproducing a Twitter convo in a blog is kind of hideous)

[@philswenson] if you want to know why groovy sucks, click here: http://pastie.org/583115
[@joshareed] @philswenson It took me a second to diagnose your problem. Did you want Groovy to say: "Hey joker, actually import the classes you're using"
[@joshareed] @philswenson Apparently Ruby has some magical mind-reading interpreter/compiler that saves you from yourself?

[@philswenson] @joshareed why the extra 500 lines of crap? in java or jruby that stacktrace would have been 1/50 the size. that's my point
[@joshareed] @philswenson re: Java guess that's the trade off for Groovy dynamics. Ruby's (http://bit.ly/IagLJ) is not any better [Note: Nambu mangled the original link]

[@philswenson] @joshareed Ruby's stack dump = 67 lines. Groovy's = 222 lines. Not as different as I said, but still...
[@joshareed] @philswenson # of lines doesn't matter when you see the cause of the prob in the first 10 lines, does it? You don't have to keep reading...
[@joshareed] @philswenson and was the 67 vs 222 equivalent programs in each? I'd be interested in comparing the source of each

[@philswenson] @joshareed this was a case where the cause was obvious (it usually isn't). isn't groovy in large part about succinctness over java?
[@joshareed] @philswenson how much time do you spend looking at stacktraces that this is hang up for you? Write a 3 line .findAll{} to filter traces
[@joshareed] @philswenson and if you want to stick with stacktrace length as your argument then you won't be plain old Java traces with JRuby

From my perspective, this isn't a JRuby vs Groovy debate even though both languages were brought up in the conversation. Both are two different ways to skin a cat but they ultimately get you to the same place. Which you choose to use is more a matter of personal preference than the actual merits of the language.

What I'm more interested in is how important/serious is the stacktrace issue that Phil Swenson argues? I've been writing Groovy for a couple years now and can't remember (off the top of my head) a stacktrace from Groovy that was so confusing I couldn't figure out the problem. I'm sure there are some, especially when you start getting deep into the Groovy innards, but I'm guessing that's also the case with other languages on the JVM, like JRuby.

All dynamic languages built on the JVM introduce a certain level of indirection (by necessity), so are Groovy's stacktraces that much more hideous than JRuby's? What qualifies as hideous? I think length is a naive measure because the cause of the problem is likely to show up in the first dozen lines. Who cares if it goes on for another 200 lines? Length is also easily manipulated. You could write a simple findAll closure that sanitizes the stacktrace by removing all the lines that start with 'sun.reflect' or 'org.codehaus.groovy.runtime'. I have never once run into a problem that could be tracked to one of those lines in the stacktrace. So now does that make Groovy better than JRuby because the stacktrace is shorter?

I'm sure this is just a case of me being used to seeing Groovy stacktraces, so I'm used to feel of them and can quickly hone in on the cause of the problem. Likewise I'm sure Phil is used to [J]Ruby errors which probably look much different than Groovy's. I say probably because the two example put forth didn't look all that dissimilar IMO but were not from the same problem so it was an apples to oranges comparison.

Anyways, how important are stacktraces when making the decision to use a particular language? Are they important enough to declare one language's superiority over another? Are they worth focusing on to improve Groovy's ease-of-use?

Griffon Installer Plugin

Last week Andres Almiray and I released a new version of the Griffon Installer plugin. This version adds support for creating native Mac app bundles for your Griffon application, as well a few refactorings to make the generated artifacts more consistent. In this post, I'm going to walk you through the process of creating a set of native launchers for your application. A future post will explain the process of creating installers.

Getting started using the installer plugin is simple:
griffon install-plugin installer

This will fetch the plugin and install it into your Griffon app. The plugin adds several new targets. All of the launcher-related targets are broken into two steps: a prepare step that copies all of the configuration files for that particular launcher into your application, and a create step that actually generates the native launcher. The prepare targets only need to be run once for your project. They give you a chance to tweak the launcher configuration files. The create targets are run every time you want to make a release.

The plugin provides launchers for the following platforms:

• Linux
  
• Mac
• Windows
• Executable Jar

The plugin also provides two other convenient targets, prepare-all-launchers and create-all-launchers which invoke the prepare- and create- targets for the four platforms above.

We'll use these convenience targets to create launchers for all platforms:
griffon prepare-all-launchers

This will create several new files for you:

• installer/jar - the executable JAR launcher directory
• installer/jsmooth - the Windows launcher directory
• installer/linux - the Linux launcher directory
• installer/mac - the Mac launcher directory
• installer/jar/MANIFEST.MF - customize the manifest of the executable JAR
  
• installer/jsmooth/$appName-icon.png - customize the .exe icon
  
• installer/jsmooth/$appName.jsmooth - customize the .exe options
  
• installer/mac/$appName.icns - customize the Mac icon

Once you are done customizing the configuration files, invoke the
griffon create-all-launchers target to actually create the launchers. This will create all of the launchers in the installer/$platform/dist directories and create archives of the launchers:

• installer/jar/dist/$appName-$version.jar - the executable jar
  
• installer/linux/dist/bin/$appName - the Linux launcher shell script
  
• installer/linux/dist/$appName-linux-$version.zip - a zip of the Linux launcher
  
• installer/mac/dist/$appName-$version.dmg - a disk image of the Mac launcher [only created if on a Mac]
  
• installer/mac/dist/$appName.app - the Mac application bundle
• installer/jsmooth/dist/$appName-windows-$version.zip - a zip of the Windows launcher
  
• installer/jsmooth/dist/$appName.exe - the Windows launcher
• installer/windows/dist/$appName-windows-$version.zip - copied from the JSmooth directory
  
• installer/windows/dist/$appName.exe - copied from the JSmooth directory
  

As you make changes to your code, simply invoke griffon create-all-launchers and your latest changes will be packaged up. If you increment the version number of your app, the created artifacts will be updated to match.

Hopefully the Installer plugin makes it easy to distribute your Griffon applications to users on various platforms. In a future blog post, I'll cover creating installers for when a simple zip file is not enough.