I have all but abandoned this blog. I think it has been over a year since I posted anything here. At this point, writing here reminds me of Forest Whitaker's character in the movie Phenomenon telling his story over a radio that he knows no one is listening to. That is fine.
My parents divorced when I was 10 years old. My Mother was put in a position where she had to take action. She put myself and my 2 sisters in the car and drove across the country to St. Louis where she had grown up and where her family lived. We had made the trip before for summer vacations but this time it was for good. I can only imagine how terrifying this must have been for her. Imagine a 10 year old car, kids 10, 12 and 13, some clothes and nothing else, nothing. I expect many people couldn't do it.
We got to St. Louis where there was lots of family support. My Mother had 2 brothers and a sister all in St. Louis along with her parents. Her sister Brenda took us into her house. She had a great place in a great neighborhood in the suburbs. Brenda was a single Mom with 3 kids of her own but her home was ours. I was young enough that I would not have been involved in financial discussions but I am sure this was a hardship for her take on 4 more people. My Mother had been a housewife and I think she left our home in Virginia with no money. If she had any money, I don't think it could have been very much. 3 kids, no money, no career.
During those first few months when we lived at Aunt Brenda's house, it really was a pretty good time for me. I spent time with my cousins. We had a great place to live. We did a lot of fun things on the weekends. It was tough working out the deal with my Dad no longer being with us but the day to day was good and the reason it was good is that Brenda took us in and made sure we had everything we needed. My grandparents, Uncles and Aunt were all there to provide support in lots of ways but it was Aunt Brenda's house we lived in and she bore a lot of the burden. I doubt she ever gave it a thought.
Aside from my Mother, it may be that Brenda is most responsible for our survival during that time, that of myself my Mother and my sisters. When I think about the time immediately following my parents' divorce, I think about the time I spent living in her house. We weren't living in a crappy motel or worse. Because of her we lived in a fantastic place and had everything we needed.
Today, Brenda's battle with cancer has come to a crushing end. I am crushed. I am crushed as I think about my cousins, her kids who are without her. I am crushed as I think about my Mother who just 2 months ago lost her Mother and now her sister.
Brenda was a tiny woman but a feisty take charge kind of woman. She didn't take any shit from anyone and if I worded it any other way, she might have taken offense.
I thank Brenda for everything she did for us. If I was a poet I would write a tribute to her. If I could paint I would paint a tribute to her. As it is, I will be thinking about her and the rest of the family and will do my best to be inspired by what she did for me and my family.
Today's Loss Thursday, August 18, 2011
Switching Versions Of Grails (and other tools) Friday, April 23, 2010
I have a little trick that I have used for many years to switch back and forth between versions of development tools. For example, because of the work that I do day to day I often need to switch back and forth between different versions of Grails. Occasionally I will execute this trick while sitting with another developer or during a live coding presentation at a conference without even thinking about it. Often someone will notice and and stop me to ask "what was that?".
I have a directory below my HOME directory called Tools. This Tools directory is where I install development tools like Groovy, Grails, Gradle, Ant etc. For some of those tools, I may want to have numerous versions of the tool available. For example, I have the following subdirectories below Tools...
grails-1.0.5
grails-1.1.1
grails-1.1.2
grails-1.2-M4
grails-1.2.0
grails-1.2.0.RC1
grails-1.2.0.RC2
grails-1.2.1
grails-1.2.2
grails-1.3.0.RC1
grails-1.3.0.RC2
One thing I might do when I need to use a specific version of Grails is something like this...
export GRAILS_HOME=~/Tools/grails-1.2.2
export PATH=$GRAILS_HOME/bin:$PATH
One limitation of that approach is it is a lot of tedious typing. Another is that the change would only apply to the shell where that was executed. Normally if I am working with a particular version of Grails, I want that version to be in play in all open shells.
Instead of pointing GRAILS_HOME at a particular version of Grails, I create a symlink at ~/Tools/grails and that link points to one of the specific Grails version directories. GRAILS_HOME points to that symlink. If I am currently using Grails 1.2.2 and I want to switch to 1.3.0.RC2, I just move the symlink and leave GRAILS_HOME and PATH alone.
Moving the symlink is easy enough but I simplify it further by defining aliases in my ~/.profile. Those look something like this...
alias gr105='rm ~/Tools/grails && ln -s ~/Tools/grails-1.0.5 ~/Tools/grails'
alias gr111='rm ~/Tools/grails && ln -s ~/Tools/grails-1.1.1 ~/Tools/grails'
alias gr112='rm ~/Tools/grails && ln -s ~/Tools/grails-1.1.2 ~/Tools/grails'
alias gr12='rm ~/Tools/grails && ln -s ~/Tools/grails-1.2.0 ~/Tools/grails'
alias gr121='rm ~/Tools/grails && ln -s ~/Tools/grails-1.2.1 ~/Tools/grails'
alias gr122='rm ~/Tools/grails && ln -s ~/Tools/grails-1.2.2 ~/Tools/grails'
alias gr130rc1='rm ~/Tools/grails && ln -s ~/Tools/grails-1.3.0.RC1 ~/Tools/grails'
alias gr130rc2='rm ~/Tools/grails && ln -s ~/Tools/grails-1.3.0.RC2 ~/Tools/grails'
# use my local development copy of Grails
alias grdev='rm ~/Tools/grails && ln -s /Users/jeff/Projects/grails/core ~/Tools/grails'
Now if I want to use Grails 1.2.2 I just open a shell and type "gr122".
I use the exact same approach for other tools that I may want to easily move from version to version.
I do all of this on OS X. The same trick should work on Linux. I don't know enough about cygwin to know if this can work on Windows or not. I expect that it probably would.
That is all I have. It isn't any big deal but is one of those little things that over the years numerous folks have asked me about and then expressed that they liked it well enough that they were going to do the same.
Enjoy!
Grails, SpringSource And Clojure Thursday, July 30, 2009
I recently developed a Grails plugin which provides support for easily accessing Clojure code in a Grails app. The details of how the plugin works are covered at http://grails.org/plugin/clojure. That page includes a link to a brief video demonstration which is available at http://s3.amazonaws.com/jeffscreencasts/grails_clojure_demo.mov. Check it out.
Shortly after publishing the plugin I posted something about it on Twitter. Not too long after that a couple of other SpringSource folks tweeted about Clojure (here and here). I got a couple of questions (in jest I am sure) about SpringSource and Clojure. "Is SpringSource Moving To Clojure?". Of course not. SpringSource is not moving to Clojure. SpringSource is all about helping folks build serious applications for the JVM and most of that is done in Java. This is not news. I work on Groovy and Grails. Much of what I do is in Groovy. This too is not news. Making it easy for folks to use languages like Scala and Clojure while taking advantage of all the great stuff that Grails has to offer, that is appealing to me and that is why I developed the Clojure plugin.
Clojure is a really interesting language. There are others. The fact that 3 folks from SpringSource have expressed some kind of interest in Clojure shouldn't be all that surprising. There are probably even more folks at SpringSource who have some kind of interest in Clojure but for entertainment, lets focus on the 3 mentioned...
I am honestly not sure how many technologists work for SpringSource but for the sake of having a number to work with, lets say there are 50. Lets also say that Clojure is interesting enough that 15% of JVM developers are interested in learning more about it. I can't back that number up with any research, lets just go with it. If 15% of JVM developers are interested in the language and you take a random group of 50 JVM developers (the 50 in question are certainly not 50 random developers, these are the edge cutters which probably makes them more likely to be interested in keeping an eye on what is new, but work with the idea that they are random)... Do the math. No, really... Do the math. Do the math to figure out the likelihood that 3 of the 50 would be interested in Clojure. I challenge you to do the math in Clojure and post your solution in a comment here. Do it in Scala, Do it in Groovy. Pick a JVM language and do the math.
The simplest solution is probably not very interesting. Prefer a solution that shows off something interesting in your language of choice.
Hmmm... are you more likely to need to refer to the Clojure book, or the high school math book? ;)
Now, you have one more reason to tinker with a new language.
Enjoy.
Grails 1.1 beta3 Is Out! Thursday, January 29, 2009
We are closing in on the much anticipated release of Grails 1.1. Today beta 3 was released. See the release notes.
A new feature that has not been documented yet involves new validation capabilities. Up to this point, domain classes and command objects within a Grails app have supported really powerful validation capabilities. See section 7 in The User Guide for info on how that works. What is new is now you can apply those same validation capabilities to any class within a Grails app, not just domain classes and command objects. Making a class validateable involves defining a static property called "constraints" and assigning a closure, just like you would in a domain class or a command object.
Second, you have to tell Grails about your validateable class. You have 2 options for doing that. One option is to mark you class with the org.codehaus.groovy.grails.validation.Validateable annotation. Another option is to define your validateable classes in grails-app/conf/Config.groovy by assigning a value to the grails.validateable.classes property. That would look something like this...
grails.validateable.classes = [ com.mycompany.dto.SomeClass, com.mycompany.SomeOtherClass]
An annotated class might look something like this...
// src/groovy/com/companyname/SomeClass.groovy
package com.companyname
import org.codehaus.groovy.grails.validation.Validateable
@Validateable
class SomeClass {
Integer age
String name
static constraints = {
age range: 16..66
name blank: false, size: 5..35
}
}
Note that if you are using the annotation based approach, Grails will search all classes in the app to find all of the @Validateables. While that isn't really a performance problem, you can tune that a bit by specifying some specific packages that Grails should search. To do that, assign a value to grails.validateable.packages in grails-app/conf/Config.groovy like this...
grails.validateable.packages = ['com.companyname.dto', 'com.companyname.someotherpackage']
If the grails.validateable.packages property has a value then Grails will only look in those packages (and packages below those packages) for classes marked with @Validateable.
While this is still beta software, I think the feature will end up being delivered in the final release pretty much like it is described above. If you have any input on that or any other features in Grails. We would love to hear from you. Bring it to the mailing list or file a JIRA issue.
Enjoy!
Getting Groovy With "with" Thursday, November 13, 2008
UPDATE 12/15/2008: I committed a change yesterday that changes the behavior of the .with method to use DELEGATE_FIRST as the resolveStrategy instead of OWNER_FIRST. If you are not sure what that means, you should by the end of this post.
Strange enough title.
Let's start with a hypothetical conversation between a geeky developer and his much less geeky wife:
Jeff: Betsy, how are you?
Betsy: I am fine thanks. How are you?
Jeff: Betsy, I am fine thank you.
Betsy: Great.
Jeff: Betsy, you know my birthday is the day after tomorrow right?
Betsy: Yes, I haven't forgotten. You mention it about 9 times a day you know.
Jeff: Betsy, yes I know. Are we going to have an ice cream cake?
Betsy: Yes, I think that would be good.
Jeff: Betsy, are you going to buy me the new Opeth DVD?
Betsy: I will get it for you but that music sucks big time.
Jeff: Betsy, that is awesome. Thank you.
Betsy: Why do you keep saying "Betsy" at the beginning of every sentence?
Jeff: Betsy, I guess I am used to inflexible languages which aren't very expressive.
Um, what does any of that have to do with Groovy? Well, lets talk about the problem with this conversation (aside from the lady's lack of appreciation for Swedish heavy metal). What is wrong is Jeff begins each sentence with "Betsy". Why might he do that? One reason is so Betsy knows that he is talking to her. Clearly this isn't necessary. It isn't necessary because she already knows he is talking to her. A context has been established which makes the addressing unnecessary. Jeff began the conversation by addressing Betsy, they probably made eye contact and were in close proximity. Once the conversation started, there isn't much question about who each sentence is being directed to.
Again, what does any of that have to do with Groovy? Lets press on...
Consider the following Java code which prints out a specific date.
// PrintIndependenceDay.java
import java.util.Calendar;
import java.util.Date;
public class PrintIndependenceDay {
public static void main(String[] args) {
Calendar calendar = Calendar.getInstance();
calendar.clear();
calendar.set(Calendar.MONTH, Calendar.JULY);
calendar.set(Calendar.DATE, 4);
calendar.set(Calendar.YEAR, 1776);
Date time = calendar.getTime();
System.out.println(time);
}
}
Groovy developers can look at that and find quite a bit of noise that doesn't really have anything to do with what the code is trying to do but I want to focus on one specific thing. That one thing is all of the interaction with the calendar variable. Notice that we call clear() on the calendar, then call set() several times and later call getTime() on that same variable. All of those calls are prefixed with "calendar." so the compiler knows what we want to do. If we called "clear()" instead of "calendar.clear()", what would that mean? Are we calling the clear() method in this class? If that was our intent, it would not work because there is no clear() method. We have to prefix the call with an object reference so the compiler knows where to send the request. That seems to make sense. However, if we are going to do a bunch of things "with" the same object, wouldn't it be kind of nice if we could somehow do all of those things without all the repetition. Specifically, it might be nice if we could get rid of all of those "calendar." prefixes.
On to Groovy...
The following Groovy code does the same thing that the Java code above does.
// PrintIndependenceDay.groovy
def calendar = Calendar.instance
calendar.with {
clear()
set MONTH, JULY
set DATE, 4
set YEAR, 1776
println time
}
Wow. That is a good bit cleaner than what we started with. Part of the reason for that is we were able to get rid of all of those "calendar." prefixes. What allowed us to do that is calling the "with" method on the calendar object and passing a closure as an argument. What we have done there is establish a context that says "do all of this stuff with this calendar object". When the closure executes, the calendar is given an opportunity to respond to method calls like clear() and set() and the implicit call to getTime() when referring to the "time" property which is being passed to println. Likewise, the references to MONTH, JULY, DATE and YEAR properties are also being handled by the calendar object.
That is pretty slick. Lets dig just a little deeper to get a little better understanding of what is really going on.
Groovy closures have a delegate associated with them. The delegate is given an opportunity to respond to method calls which happen inside of the closure. Here is a simple example:
// define a closure
def myClosure = {
// call a method that does not exist
append 'Jeff'
append ' was here.'
}
// assign a delegate to the closure
def sb = new StringBuffer()
myClosure.delegate = sb
// execute the closure
myClosure()
assert 'Jeff was here.' == sb.toString()
When the closure is executed, those calls to append() in the closure end up being sent to the delegate, the StringBuffer in this case.
Something similar is happening in the Groovy calendar code above. A closure is being passed to the with() method. That closure is calling methods like set() and getTime() which don't really exist in that context. The reason those calls don't fail is the with() method is assigning a delegate to the closure before it is executed. The delegate being assigned is the object that the with() method was invoked on. In the calendar example, the delegate is the calendar object. Something like this is happening...
def closure = {
clear()
set MONTH, JULY
set DATE, 4
set YEAR, 1776
println time
}
def calendar = Calendar.instance
closure.delegate = calendar
closure()
This code does the same thing as the first Groovy example. Obviously the first one is cleaner.
I sort of lied a bit, or at least left out a detail that may be significant. The closure that is being passed to the with() method is really being cloned and it is the clone that is assigned the delegate and executed. This is a safer approach than monkeying with the original closure. If the reasons for that aren't clear, the explanation is another story.
Another bit of info that is missing here is the strategy that a closure uses to decide when to send method calls to the delegate. Each Groovy closure has a resolveStrategy associated with it. This property determines how/if the delegate comes in to play. The 4 possible values for the resolveStrategy are OWNER_FIRST, DELEGATE_FIRST, OWNER_ONLY and DELEGATE_ONLY (all constants defined in groovy.lang.Closure). The default is OWNER_FIRST. Consider the owner to be the "this" wherever the closure is defined. Here is a simple example...
class ResolutionTest {
def append(arg) {
println "you called the append method and passed ${arg}"
}
def doIt() {
def closure = {
append 'Jeff was here.'
}
def buffer = new StringBuffer()
closure.delegate = buffer
// the append method in this ResolutionTest
// will be called because resolveStrategy is
// OWNER_FIRST (the default)
closure()
// give the delegate first crack at method
// calls made inside the closure
closure.resolveStrategy = Closure.DELEGATE_FIRST
// the append method on buffer will
// be called because the delegate gets
// first crack at the call to append()
closure()
}
static void main(String[] a) {
new ResolutionTest().doIt()
}
}
So you see how the with() method helps establish a context where a bunch of things may happen "with" a specific object without having to refer to that object over and over. This can help clean up code like the Java code we started with. This approach can also be really useful when building a domain specific language in Groovy, a topic for another time.
Enjoy! :)
Grails Training In Chicago Monday, August 04, 2008
We are really excited to have a 3 day Groovy/Grails training event coming up in Chicago later this month. The training dates are August 26-28. The training will be held at the Hotel Indigo in Palatine.
This is 3 days of lecture and reinforcing lab work. Attendees should expect to write a lot of Groovy and Grails code with your training expert. There is no better way to quickly get your team up to speed on the technology, well beyond the basics.
As with all G2One training events, students will receive a free 12 month license to use IntelliJ IDEA. The IntelliJ guys have done a fantastic job of building first class Groovy and Grails support for the IDE.
For a full course outline and more information, please visit http://g2one.com/training/. Any questions may be directed to training@g2one.com.
G2One QuickCast Site Launched! Wednesday, July 30, 2008
G2One have launched the G2One QuickCast site. A G2One QuickCast is fast and furious little movie demonstrating something interesting about the Groovy language and/or the Grails framework.
The first movie available there demonstrates how powerful tools like Grails and Git can work together to support a really really agile development process. Watch this movie and try to do something like this with your web framework and your VCS. If you can't, your tools are not flexible enough. :)
Enjoy!
G2One Groovy Grails Training In North America Monday, July 14, 2008
G2One have announced our Groovy/Grails North American public training schedule for the rest of the year. The schedule is available at http://www.g2one.com/training/.
Our training events are a fantastic experience. G2One are the folks who lead and sustain the development of both Groovy and Grails. No one understands the technology better than the people who build it. G2One training events give developers an opportunity to spend several days with a technology expert covering everything from fundamentals to advanced language and framework features. The sessions include a perfect mix of lecture and reinforcing lab work. That hands on approach is a great way for developers to internalize the details. There is no better way to quickly get a team up and running with the technology.
Grails Plugin For Hudson Thursday, June 19, 2008
I am pleased to announce that we have worked up a Grails plugin for Hudson. Hudson is a really slick continuous integration server. Check out their site for more info on the engine itself.
It has always been possible to build Grails apps from Hudson but in the past this has involved writing shell scripts that are triggered by Hudson. This works but is not the slickest solution. What you really want is for the CI server to have knowledge of the fact that the project you are building is a Grails app and that knowledge will allow the tool to be more efficient about carrying out the build and also allow the CI server to provide Grails specific options for the build. This is where the new Grails plugin is heading.
Right now the plugin is very basic. In the system configuration screen you may configure as many Grails installations as you like. This is useful for situations where the same CI server may be building multiple projects with different version of Grails or maybe even building multiple copies of the same project with multiple versions of Grails. Below is a screenshot of the system configuration screen:
Notice that there is built in validation to make sure you have entered a valid path to your Grails installation.
When configuring a project in Hudson you have a lot of options for what should happen at build time. The Grails plugin adds a "Build With Grails" option and if that option is selected you can select from a list of common build targets to execute as well as type in any arbitrary targets you may want to execute. This is useful for executing Grails commands that are not in the list of checkboxes and for executing your own custom Grail scripts that may be part of your project. Below is a screenshot of the project configuration screen:
The first version of the plugin has not been released yet but will be soon. In the meantime, I would be happy to hear what kinds of capabilities you would like to see the plugin provide. Even in its current very basic state, the plugin is very useful as it makes configuring a Grails project in Hudson drop dead simple.
St. Louis Dynamic Language Interest Group Saturday, June 07, 2008
I have created the St. Louis Dynamic Language Interest Group at LinkedIn. If you have a special interest in dynamic languages and are in the St. Louis area or are close enough to the St. Louis area that you would like to be involved with the group, please take a minute to visit the group at LinkedIn and join us.
More information is coming regarding the goals of the group and what sorts of activities we may engage in. I want to give the group some time to populate before moving forward with those details.
If you have any questions about the group in the meantime, please don't hesitate to let me know.
Jeff Brown
Director - North American Operations
http://www.g2one.com/
New Grails Mail Plugin Wednesday, June 04, 2008
The new Grails Mail Plugin is really slick stuff. Very little effort has gone in to the thing so far and there is more to come but even in its current state this is really nice. More details are available at http://grails.org/Mail+Plugin but basically you get a method called 'sendMail' added to your controllers (or you could use an autowired mailService) that accepts a closure and the contents of the closure express the details of the message being sent. A simple example looks like this...
sendMail {
to 'fred@g2one.com'
subject 'Hello Fred'
body 'How are you?'
}
Take a look at the docs for more information. This is good stuff already. I think the simplicity of sending a message like this is pretty impressive but more impressive is how easy it is to build support for something like that in a dynamic language like Groovy. More and more folks are taking advantage of the Grails Plugin System to easily add capabilities like this to their web apps.
Enjoy!
Groovy Grails Training From G2One and Callista Enterprise Wednesday, May 21, 2008
G2One, Inc. and Callista Enterprise AB have announced a partnership to support Advanced Groovy and Grails training in Scandinavia.
Göteborg 2008-09-08
Stockholm 2008-09-15
Malmö 2008-09-22
The 3 day comprehensive course covers details from intro to advanced for both the Groovy language and the Grails framework. The course description may be found here.
As with all G2One training events, students will receive a free 12 month license for IntelliJ IDEA. IDEA's JetGroovy brings fantastic support for both Groovy and Grails to the IDE.
Please contact us at training at g2one dot com with any training related inquiries.
North American dates coming soon...
Pre JavaOne Groovy/Grails Meetup Next Monday Wednesday, April 30, 2008
We have been busy preparing for JavaOne and it is finally almost here. Yay!
We hope to see you at the G2One / NFJS Meetup Monday night. Click the link for all of the details and be sure to click the "register" link. Registration is free and the event promises to be a load of fun. Come hear the latest Groovy and Grails news from G2One, the latest word from the respected NFJS tour and finally a great expert panel discussion. Author signed copies of Scott Davis' Groovy Recipes book and Venkat Subramaniam's Programming Groovy book will be raffled off.
Don't miss it.
Between now and then, I hope to see some of you in Denver this weekend. :)
Another Big Week For Groovy And Grails Monday, February 18, 2008
This is definitely going to be another big week for Groovy and Grails. The Grails 1.0.1 point release was published today. This release contains over 40 enhancements over the 1.0 release from just a couple of weeks ago. The Grails community has been buzzing at full steam since the 1.0 release. This is fantastic stuff!
This Wednesday I am heading to the great New York City to speak at their JUG about Groovy. That is going to be a lot of fun. Immediately after that is the event that so many people (including myself) have been looking forward to for a long time. That of course is The Groovy Grails Experience in Reston Virginia, starting on Thursday Feb. 21 and running through Saturday the 23rd. It will be a while before this many of the key players in the Groovy/Grails community get together in one spot to talk shop. I can't wait!
Jeff Brown Interview At Groovy Zone Saturday, February 09, 2008
I had the great pleasure of doing an interview recently with Steven Devijver for The Groovy Zone. Today, that interview was published. Check it out at http://groovy.dzone.com/news/jeff-brown-grails-10-and-beyon. In the interview we discussed the Grails 1.0 release, the great plugin story that Grails has to offer, the upcoming Groovy Grails Experience and more. I want to thank Steven for the opportunity.
The Groovy And Grails Communities Continue To Buzz Thursday, February 07, 2008
A lot of things are going on right now in the Groovy and Grails communities. I have been really busy myself and have a lot of exciting things coming up. I am very excited about my role as Director of North American Operations with G2One and that is really keeping me busy.
I spent the first part of this week out in Silicon Valley with Graeme Rocher and Peter Ledbrook working on some really exciting Grails stuff. It was great to be out there with Graeme on the day that Grails 1.0 was released. The whole development team and user community have done an incredible amount of work on Grails to get to this point but I think Graeme himself deserves the props. Graeme conceived the thing and has been driving it very hard from the beginning with the focus and vision necessary to get the framework to this point. Well done Graeme!
Later this month I am going to have the pleasure of speaking at The New York Java SIG about Groovy. I speak at JUGs all the time but this one in particular I am looking forward to. A few months ago I was on the schedule to speak out there and due to an incredible string of bad luck, I wasn't able to make it. My flight was cancelled. My replacement flight was delayed. Once my delayed flight took off we ended up circling in the air for a long time waiting for some weather to settle down. Once I got to New York we found it near impossible to get in to Manhattan because it just happened this was the day of the huge water main explosion. I ended up spending the entire day on airplanes and in terminals just so I could get to my hotel, sleep and then fly home the next day. This time, things will no doubt go much more smoothly. I can't wait to get out there.
When I leave the New York Java SIG I will be heading straight to the airport to get to the event that I am even more excited about. That is The Groovy Grails Experience in Reston VA beginning on Feb. 21. The event is being put on by the same folks who have been putting on the hugely successful No Fluff Just Stuff symposiums for years now so I know it is going to be a great event. This is 3 days packed with talks all about Groovy and Grails. Of all the shows I do this year, this is probably going to end up being the one that is most exciting for me personally. All of my friends from the Groovy and Grails communities are going to be there and I know everyone is going to have a great time. This is the biggest Groovy/Grails event ever to be put together. It isn't often that we get an opportunity like this to get together so many players in the Groovy/Grails communities to talk about the technology. For folks who are interested in the power of Groovy and Grails and the vast possibilities that dynamic languages bring to the JVM, I can't think of a better way to spend 3 days. I am completely pumped about this event.
The Groovy Grails Experience Wednesday, December 12, 2007
The first major Groovy / Grails conference in North America is just around the corner. The Groovy Grails Experience is going to be in Reston Virginia on Feb 21-23, 2008. The event is bringing key players in the Groovy and Grails community together from all over the globe to put on what is sure to be a really exciting event.
Check out the speaker list. Graeme Rocher! Jason Rudolph! Dierk Koenig! Scott Davis! Andy Glover! Venkat Subranamium! Neal Ford! Brian Sletten! The list goes on and on... This really promises to be a fantastic event. I am really looking forward to it.
The event is coming along at a great time. Groovy is finishing up a really really exciting year that started with the release of 1.0 and ran right up to the release of 1.5 last week. We have seen a bunch of new public facing Grails sites go live this year as well as lots of internal application development being done with Grails. Grails is closing in on the very much anticipated 1.0 release.
Good times continue!
Grails 1.0 RC1 Has Been Released Tuesday, October 16, 2007
Grails 1.0 RC1 has been released! See the release notes for details about many of the new features.
This is fantastic news for the Groovy and Grails community.
In a few hours I am getting on a plane to London to speak at The Grails eXchange. I am really looking forward to finally meeting in person some of the folks I have been working with for so long now.
Maverick On Rails Sunday, September 09, 2007
Interesting Groovy Loops Detail Tuesday, August 07, 2007
While fixing a bug in Grails last night I came across something that I found interesting. At first I was really puzzled but now that I know what is going on, it all makes perfect sense.
A unit test that had been passing for some time just started failing. I isolated a specific revision of a specific file that seemed to be causing the test to fail. The test passes with version X of the file and the test fails with version X+1 of that file. I spent some time diffing the 2 revisions and couldn't find anything that seemed relevant. Eventually I figured out the specific change that was causing the failure. There was code that looked something like this...
someCollection.each { someElement ->
// do something with someElement
}
That code had been changed to look something like this...
for(someElement in someCollection) {
// do something with someElement
}
The code inside the loop was exactly the same for both versions. The only difference is the original code was using "each" to iterate over the collection and the new code was using a "for" loop to do the same thing. I puzzled over that for a bit trying to figure out what was going wrong and after discussing with my co-developers the problem eventually became clear. Code inside the loop was making use of someElement inside of a closure and later that closure was being executed. Consider this...
def listOfClosures = []
def numbers = [1, 2, 3]
numbers.each { number ->
listOfClosures[number] = { println "number is $number" }
}
listOfClosures[1]()
listOfClosures[2]()
listOfClosures[3]()
As you might guess, the output from that looks like this...
number is 1
number is 2
number is 3
Now consider this...
def listOfClosures = []
def numbers = [1, 2, 3]
for (number in numbers) {
listOfClosures[number] = { println "number is $number" }
}
listOfClosures[1]()
listOfClosures[2]()
listOfClosures[3]()
The output from that looks like this...
number is 3
number is 3
number is 3
With the "for" loop approach, the same "number" variable is used each time through the loop so by the time the loop completes, the value of "number" is 3 which is what is used by the time the closures execute. With the "each" approach, a separate variable is used for each iteration so each closure accesses the "number" that was around when the closure was declared. None of that is broken or a bug. I believe it is all working as it should.
Thanks to Charles Nutter and Graeme Rocher for helping with that.