JavaRanch: Object Oriented Scripting

Building object graphs of expressions written in template scripting languages

Mon, 28 Apr 2008 09:52:15 MDT

I am working on a client-server application which allows the user to define application domain-specific expressions on the server. These expressions are then converted to a Java object tree and stored in the database in an XML form. The server then send the expression to the client, who evaluates it in the context of its own domain and returns the result to the server.

I am looking for a tool which supports a template language, such as Velocity, for defining expressions and has an API that generates a Java object graph for a given expression. One such imaginary technology would be the one that converts a template language expression to JavaScript expression and then provides the API that converts the JavaScript expression to an ...

Programming Groovy - Avaliablity in India

Mon, 28 Apr 2008 04:06:15 MDT

Hi Vengat,

Any idea when local(cheap) paper back edition of Programming Groovy will be available in India

remoteFunction with Effects

Fri, 25 Apr 2008 08:42:06 MDT

Hi
I am refreshing a Div with remoteFunction like this

code:

 ${remoteFunction(action:'nextPage',controller:'controller',update:'divRefresh')}

The previous content goes away and refreshes quickly .
can i Effect.Fade the previous div content and Effect.Appear the next content of Div with remoteFunction?

Does Groovy got the muscles?

Tue, 15 Apr 2008 11:36:58 MDT

Hi.
Python and Ruby are so much powerful and capable scripting languages.
Does Groovy has the same power and features as Python & Ruby or it just provides a simplified syntax around Java's ones?
Thanks.

Does Groovy got the muscles?

Tue, 15 Apr 2008 03:29:19 MDT

Enterprise applications with Python

Tue, 15 Apr 2008 03:23:19 MDT

Hi.
Is it possible to create enterprise applications (in the same context of Java EE applications, highly concurrent, distributed ...) with Python?
I'm still playing around Python but it seems to it is best fits in public web sites (YouTube), news sites, forums ...
Does the same is true for PHP and Rails?
Thanks.

Groovy+ grails +display flash image

Mon, 14 Apr 2008 07:29:17 MDT

I have uploaded a flash image to mysql table as mediumblob datatype.
I am trying to show that flash image like this

code:

 <img src='/web-appex/widget/flashImage_show/id' />

and the closure flashImage_show is like this

code:


 def flashImage_show = {
 def widget= Widget.get( params.id )
 if (!widget || !widget.flashImage || !widget.mimeType) {
 response.sendError(404)
 return;
 }
 response.setContentType(widget.mimeType)
 response.setContentLength(widget.flashImage.size())
 OutputStream out = response.getO...

a program

Mon, 14 Apr 2008 01:31:16 MDT

Hello to all
I need a simple and small program that be Aspect orinted in java or C++ can any one help me. If you know please send it to me

* Winners: Programming Groovy: Dynamic Productivity for the Java Developer

Sat, 12 Apr 2008 04:05:10 MDT

First, a big thanks to Venkat Subramaniam for being here to promote the book Programming Groovy: Dynamic Productivity for the Java Developer (http://www.amazon.com/gp/product/1934356093?tag=jranch-20).

The winners are:

Joe Hollow
Dave Klein
Rick Reumann
Jothi Shankar Kumar Sankararaj

Please send your snail mail address to bookpromotion AT javaranch DOT com. To ensure the quickest response, please provide the following:

Your name (first and last - preferably the one you use on Javaranch)
Address
Phone Number

Also, please include the following as the subject of your Email.

Book Promo Winner - Programming Groovy: Dynamic Produc...

I've been waiting for this book

Fri, 11 Apr 2008 14:47:09 MDT
I saw Venkat at No Fluff Just Stuff recently, and he gave a couple of talks about DSLs and BDD in groovy. Does this book cover those subjects in more depth?

Also, does this book get into grails at all? There doesn't seem to be a lot of books on the subject, and tutorials are few and far between outside of codehaus.

When doing a side by side comparison to Scott Davis' book Greasing the Wheels of Java, how would you say that this book differs?

Thank you folks

Fri, 11 Apr 2008 07:15:08 MDT
I want to say thank you for everyone who participated in the promotion of my book "Programming Groovy." Thank you for the questions, your comments, your analysis, your answers, and most of all, your interest and passion to programming in general and Groovy in particular. It was a pleasure being here and best wishes to all. Thanks to the kind folks at Java Ranch for inviting me for the promotion and for providing a nice forum to meet you all.

Best wishes and warm regards.

Question on the Groovy book

Thu, 10 Apr 2008 22:13:07 MDT
Hi Author,

Yesterady I started to explore Groovy and the same day I bought the Groovy in Action and it looks as a good starting point. My question to you here is

(1) How do you compare your book with Groovy in Action

(2) Up to what extent does the book makes us familiar with Groovy? After reading your book, can I start using Groovy for my enterprise web apps?

(3) Does your book cover any Groovy specific frameworks like we have for Ruby (Ruby on Rails)?

Very much eagar to know on the third point.

How to convince management to use Groovy

Thu, 10 Apr 2008 21:53:06 MDT
Our company is setting standards of what developers can and can not use. For instance languages are .Net on the Windows side and Java for Unix projects. The .Net developers are allowed to use VBScript, but the Java developers are limited to Java only. I am trying to convince the architectural group that Groovy would be a great addition for both Windows and Unix development for scripting applications and small to medium projects. The same could be said for developing small to medium web projects with Grails instead of J2EE. Any help with convincing arguments would be greatly appreciated.

Table of Contents and a Sample Chapter

Thu, 10 Apr 2008 11:27:05 MDT
A few of you asked for more information about the book.
You can find a press release of the book here:

http://www.pragprog.com/press_releases/programming-groovy-productivity-for-the-java-developer (http://www.pragprog.com/press_releases/programming-groovy-productivity-for-the-java-developer)

You can find table of contents here:
http://pragprog.com/titles/vslg (http://pragprog.com/titles/vslg)

You can also find an excerpt of a chapter at the above URL.

In one of the posts, someone asked for the preface.
When you click on the "Groovy for the Java Eyes" excerpt,
you will also get the preface or Chapter I-Introduction.

Hope this helps.

Groovy Book Question

Thu, 10 Apr 2008 07:07:04 MDT
Hi Venkat!
Welcome to Java ranch..
Its nice to talk to you...
I'm new to Groovy.. I learned Java..and JEE..

So how much time it'll take to change to Groovy?
What exactly is Groovy.?
Is it a framework?
Is it a new technology?
Is it connected to web?

Thanks

Closures in Groovy

Thu, 10 Apr 2008 05:49:04 MDT
http://groovy.codehaus.org/Closures (http://groovy.codehaus.org/Closures)

Referring to the link above, what big difference does a closure makes when we compare it with a normal function?

Groovy vs Ruby vs Java

Thu, 10 Apr 2008 05:47:04 MDT
What could be it? I've read from google search is that Groovy is a serious competitor to Ruby. Is this true? Both Ruby and Groovy tend to do the same? Advice needed guys!

Groovy, ready for the prime time?

Thu, 10 Apr 2008 02:29:04 MDT
Hi Mr. Venkat,
First let me send to a hearty thanks for your amazing book "Practices Of An Agile Developer".
Which other scripting language that it could contend (or it is already contending) with Groovy over 'Preferred Scripting Language For JVM' crown?
While Groovy has a smooth learning curve for Java developers, aren't other languages like JRuby and Jython are much more robust?
Thanks.

Groovy as an enterprise application

Wed, 9 Apr 2008 23:27:03 MDT
My organization is fairly conservative (we are still using Java 1.4!) I was quite keen on using Groovy as it compatible with Java without the need for 'translators'.

I was met with the response 'Groovy is yet another fad' when trying to implement Groovy in small internal applications.

Do you think it is yet another fad Venkat? How do you think if I gave them your book (or a book that may suggest) to read it will give them more information about Groovy as to not dismiss it so easily?

The developers are on my side of the fence after reading Groovy recipes.

Thanks.
Praveena.

Groovy Book

Wed, 9 Apr 2008 10:51:02 MDT
Can anybody tell me which is the better of the Groovy books to buy?

Groovy Tutorials

Wed, 9 Apr 2008 02:01:01 MDT
Can you suggest a good web site about Groovy tutorials.

groovy vs scala

Tue, 8 Apr 2008 23:15:00 MDT
Any one had to choose between these 2 JVM based scripting languages for projects?

Plans to allow breaking in a closure?

Tue, 8 Apr 2008 22:41:00 MDT
Are there any plans to allow a way a "break" from an each closure? In other words, sometimes I'd like to do ..

collection.eachWithIndex{ it, i ->
//do stuff with it
if ( someCalculation == i ) break

}

But there is no way that I see to break out of an each closure?

GroovyTestCase

Tue, 8 Apr 2008 20:47:00 MDT
How is the GroovyTestCase any different from using TestCase? Is it not just JUnit anyway?

Sun Support for Groovy

Tue, 8 Apr 2008 20:43:01 MDT
Groovy was initially supported by a JSR correct? Why has it moved away from being part of the Java Community Process? And what position does Sun take on Groovy?

How to work with Xml using Groovy

Tue, 8 Apr 2008 15:52:59 MDT

quote:

Hi,

How to work with Xml using Groovy?

Thanks
Saritha

groovy - good starter projects?

Tue, 8 Apr 2008 13:56:59 MDT
I've found a few cookbooks out there that give some good programs to write to get started learning a language. I'm curious if anyone has found some easy to medium difficulty projects that point out the good features of groovy?

I'm confused - What's groovy?

Tue, 8 Apr 2008 13:42:59 MDT
I love OO programming. In fact, I'd be willing to say I'm obsessed. I think daily in an OO style. My mornings consist of creating a new instance of the Breakfast object, .eat()ing the newest Breakfast object, and using the getDressed object on myself. And I am not joking. That is what goes through my head. But what is groovy? What is "vanilla java?"
As far as I see from examples, a groovy file is pretty much the same thing as any old Java file, so what is the difference? What is the benefit? And why is it under the OO Scripting forum? What is going on?!!

Groovy and TDD

Tue, 8 Apr 2008 12:18:59 MDT
I note that the book contains a chapter on unit testing and mocking in Groovy. I'm curious about the experiences of the authors and others doing either TDD or simple unit testing with Groovy.

Jeff

Groovy book preface?

Tue, 8 Apr 2008 12:14:59 MDT
Greetings Venkat,

I saw a link to the table of contents in one post. I also read the Amazon previews; looks promising! Are you able to post the preface to the book, or perhaps provide a bit more information here about what we might expect in the book itself (for example, how much code is there, do you use a running example, etc.) and who it's targeted at?

Thanks,
Jeff

Why choose groovy?

Tue, 8 Apr 2008 11:06:59 MDT
What differentiates groovy from other dynamic languages running in the JVM, such as Jython and JRuby? What are the benefits of choosing groovy over these other languages?

Thanks!

Groovy: better for desktop, web or both?

Tue, 8 Apr 2008 10:34:59 MDT
Hello,

I'd like to know if Groovy is more indicated to desktop development or web applications? Or both?

Thanks.

Can anyone explain the Groovy 'expando' class in simple terms?

Tue, 8 Apr 2008 09:40:59 MDT
I've read about 3/4 Groovy in Action, and one thing I keep stumbling on is the explanation of the expando class. I know it has something to do with dynamic collections, but after that it becomes fuzzy.

Can anyone explain this class in simple terms that my feeble brain can get around?

Thanks,
-Chris

Programming Groovy vs. Groovy Recipes

Tue, 8 Apr 2008 09:36:59 MDT
Hi Venkat,

I picked up Groovy Recipes @ NFJS, 2008.
I've found it very helpful for showing me how to do some stuff
without having to think about it or reference the Groovy API.
I think this is a GoodThing(tm) when learning a new language where I don't have a lot of time to devote to it, on the job.

Programming Groovy was not yet published, at the time.
(I'm pretty certain this book will cover what you covered in the meta-programming area.)

So, please, enlighten me on how Programming Groovy will help make me a groovier coder.

Trade-Offs of Groovy...?

Tue, 8 Apr 2008 09:08:59 MDT
One of the reasons I have been hesitant to invest the time and effort required to really pick up Groovy is the fact it remains a scripting language at its heart. (Obviously, this is one of the strengths so often touted as well.)

Traditionally, scripting languages have a number of weaknesses. For example, it is very easy to get them to run (due to their simple, concise syntax) --yet it is often very difficult to get them to run correctly. You very likely have to test and test and test and test to find out what went wrong. Java you can run a debugger. Is there a full-featured Groovy debugger? Can it attach to a running server and help debug?

Also, it is very easy to write some highly esoteric--or even cryp...

Groovy use

Tue, 8 Apr 2008 09:06:59 MDT
Many people ask here what is this Groovy thing about and how useful can it be, and really, what is so groovy about it.

I decided to post my 2 cents, as we've been using it (or incorporating it) into our latest product version.

The main and biggest use for us so far has been customization of the product. For me the main power of Groovy has been its relative syntactical simplicity plus tight integration with Java. Business software is rarely "one size fits all" and thus requires some way to customize certain functionality of it. If you build on Java platform, Groovy can be an answer to provide a relatively straightforward script-based customizations. Custom reports, all kinds of templates, custom functional overrides, ...

so many books on this evolving technology

Tue, 8 Apr 2008 09:06:59 MDT
Venkat,
How does your book stand out from the rest?
Do you have explanations and guides with code bases to work on them and learn?
Or is it more theoretical and left to the reader to try out the concepts?

How efficient it is in case of Multithreading?

Tue, 8 Apr 2008 08:10:58 MDT
In case of MultiThreading and in case of multiple clients in a distributed architecture how efficient it is?

does groovy require a different framework?

Tue, 8 Apr 2008 07:56:58 MDT
When we are programming java with groovy, are we using a new framework? or struts and tapestry...these are all compatible with groovy API? Is it the JVM which compiles the groovy to Java bytecodes?

grrovy's own API?

Tue, 8 Apr 2008 07:50:58 MDT
groovy has its own API like Java? can we program groovy to do database connections or make a GUI interface?

Grails

Tue, 8 Apr 2008 07:42:58 MDT
Do you cover Grails in this book?

I need metaClass advice

Tue, 8 Apr 2008 07:40:58 MDT
I need another method on String. I used metaClass to do this:
code:
String.metaClass.findAllIndicesOf = {findMe->
def foundIndices = []
def i = delegate.indexOf(findMe)
while(i>-1){
foundIndices << i
i = delegate.indexOf(findMe,i+1)
}
return foundIndices
}

However, in all of the code examples I've seen on metaClass this trick has always been inside a script. In my application, though, I'm not running scripts - I have Groovy classes. I suppose I could place this metaClass thing in the beginning of any method that needs to call it... but that sure doesn't feel right.

I thoug...

Concerns with Java+Groovy

Tue, 8 Apr 2008 07:22:58 MDT
The biggest reasons I've stayed away from scripting languages within Java are the ones you'd probably guess - maintainability and pure maintenance.

If I introduce Groovy to my code, I force another technology upon all persons who are developing on that common code base. And while that might normally happen anyway with new API/libraries, its a bit harder with something that is conceptually different.

However, with Groovy being one of many technologies that is getting a lot of word of mouth these days (at least in my office), I'd like to know a bit more about it (best tool for the job and all that). My first concern with introducing a scripting language into my java code has to be maintenance. Will most common IDEs (s...

Groovy's performance vs. Java

Tue, 8 Apr 2008 06:56:58 MDT
You knew the performance question was coming, right? How does Groovy's performance measure against Java's? I've read and heard several times that Groovy is nowhere near Java as far as performance. Is Groovy's performance improving with age?

On a related note, I've heard that "you can always write Java if Groovy doesn't perform well enough for you." While this is true, I don't like it. If Groovy doesn't perform well, its performance should be improved. I don't think the solution should be for me to go write Java. There's a reason I chose Groovy to solve the problem, so why should I have to switch to Java (even if only for a few lines of code)?

Are there people working to improve Groovy's performance?

Groovy and JMX

Tue, 8 Apr 2008 06:54:58 MDT
Hello Venkat,

In which area and how people have applied the combination of Groovy and JMX? Can you name a few and point out what the benefits are?

Thanks,
Frank

Programming Groovy vs Groovy in Action

Tue, 8 Apr 2008 06:32:58 MDT
I love books .. but, I have to ask.. with Groovy in Actino out there... what does purchasing Programming in Groovy get me?

I understand Groovy in Action is based on Groovy 1.0 etc etc.

I just always like to get a feel for "whats in it for me".. trading $$ for a new book

BTW, Venkat, I saw you speak at the NFJS 2007. Good stuff (groovy and DSLs)

What kinda Template Engine Groovy Uses?

Tue, 8 Apr 2008 06:18:58 MDT
Hi Venkat,

In the examples listed here (http://groovy.codehaus.org/Closures+-+Formal+Definition), it looks like a *template engine* is in built, through the place holders with "${}".

What kinda template engine it uses? Like Freemarker, velocity etc., or of its own? If its of its own, to what extent is is unique and beneficial than others?

Thanks,
Raghavan alias Saravanan M.

Is Groovy taking us back ?

Tue, 8 Apr 2008 06:14:58 MDT
Hi Venkat,

I found in one of the examples listed here in this thread (http://saloon.javaranch.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic&f=60&t=000376) that there was a line like "println it" etc., it sounds more of ALP (Assembly language programming) where we have commands like MOVE, STORE, LOAD etc.,

Is it taking the developers to the traditional style? Means, will it be leading us towards?

Thanks,
Raghavan alias Saravanan M.

Is Groovy an abstraction ?

Tue, 8 Apr 2008 06:04:58 MDT
Hello Venkat,

As per the discussions happening on the threads, i could get some information that Groovy works mainly on Java and its provides an abstraction to the core Java Language so as to simplify the work of developer. But in a true sense, the *real aspects* behind the scene remains the same in a program/application.

In such case, is it mere an abstraction?

Thanks,
Raghavan alias Saravanan M.

Groovy and Backend programming

Tue, 8 Apr 2008 05:00:58 MDT
Hi, Venkat. I'm primarily a backend Java programmer(non-web based). I've experimented with Groovy but find my code is approximately the same length as the Java code itself. Can you list some examples of how Groovy can benefit backend
applications?

Thanks