Anyway, better late than never, here are some of excerpts and salient features of clojure as described by “BG”.

• Clojure is a variation of LISP, but is a JVM based language so gives interoperability with the JVM.
• One can do functional programming with Clojure.
• One of the interesting things about clojure is that you can bring the domain of your problem statement into this language, rather trying to adapt Clojure to the domain.
• Clojure has profound state management capability.
• Protips for Clojure, an LISP based language for that matter
• 1) Everything, i.e every statement in LISP is perceived as a list of items.
• 2) the first item in the list, is always considered to be a function.
• As a consequence of the above, all LISP statement are read as “prefix expressions”.
• Few interesting mentions about Datatypes in Clojure ->
• 1) basic datatypes in Clojure start at Long and Double as against int and float for those from the C,C++,Java world
• 2) there exists a dedicated datatype called “Ratio” that enables much higher levels of accuracy in computation when dealing with real numbers such as ‘Pi”(22/7)
• 3)RegularExpression is a one of the built in datatypes
• 4)There is also a datatype called ‘Keyword’
• Some default datastructures built into Clojure ->
• 1)List -  its a singly linked list that grows from the front
• 2)Vector – its a collection of values indexed by contiguous integers that grows from the end.
• 3)Map – its a standard key,value pair datastructure
• 4)Sets – its a collection unique values (yes the same way we refer to sets in maths)
• One key thing about Clojure is that all datastructures are immutable and when you code with them, you only perform transformations over them and copy them over to newer items while playing around with them
• The other interesting aspect of this Clojure 101 talk was about sequences – where you can specify the first item of a sequence followed by instructions to recursively generate the next next elements of the sequence.
• Namespaces are part of the language. You can create and switch in between namespaces even while you are playing around in the commandline.
• And namespaces can be imported around as if they were packaged libraries.

These are the major things that BG spoke about. As BG mentioned at the beginning of the talk, the goal of the above points is to give Clojure aspirers a good springboard, from where they can easily jump into the world of Clojure programming.

Hope this helps someone looking for a headstart in Clojure.

Key Learnings : -
a. JavaScript’s support for OO is very different from that given by C++, Java
b. a JavaScript function is really an object with executable code associated with it. and hence every function in JavaScript gets a “this” operator which refers to itself
Example-

function displayQuote() {
    // the value of "this" will change; depends on
    // which object it is called through
    alert(this.memorableQuote);
}

var williamShakespeare = {
    "memorableQuote": "It is a wise father that knows his own child.",
    "sayIt" : displayQuote
};

var markTwain = {
    "memorableQuote": "Golf is a good walk spoiled.",
    "sayIt" : displayQuote
};

var oscarWilde = {
    "memorableQuote": "True friends stab you in the front."
    // we can call the function displayQuote
    // as a method of oscarWilde without assigning it
    // as oscarWilde’s method.
    //"sayIt" : displayQuote
};

williamShakespeare.sayIt(); // true, true
markTwain.sayIt(); // he didn’t know where to play golf

// watch this, each function has a method call()
// that allows the function to be called as a
// method of the object passed to call() as an
// argument.
// this line below is equivalent to assigning
// displayQuote to sayIt, and calling oscarWilde.sayIt().
displayQuote.call(oscarWilde); // ouch!

c. You declare and setup classes by setting up functions in their name
d. Every object in JavaScript is created as a copy of an existing example object, and every class definition, so to speak , has the keyword “prototype” associated with it giving us developers access to the prototype of the class that we are setting up.  ”Any properties and methods of this prototype object will appear as properties and methods of the objects created from that prototype’s constructor. You can say that these objects inherit their properties and methods from their prototype. “
e. Every “prototype” has a “constructor” property to it. and since the class declaration/definition itself is a function, this “constructor” property  simply refers back to this function. (some recursion this is).
f. “Every JavaScript object inherits a chain of prototypes, all of which terminate with Object.prototype, which is the ultimate base prototype for all prototypes. “
g.JavaScript supports closures. “Closure” when crudely translated to simpler english means anonymous functions. And a more specific meaning would be “A closure is a runtime phenomenon that comes about when an inner function (or an inner anonymous method) is bound to the local variables of its outer function.”

Inheritance works this way – http://javascript.crockford.com/prototypal.html

GIF images are of two varieties – the plain kind and the animating kind. And It is possible to do very basic animation in GIF images. But you can never embed an animating GIF image in a Flex application. try it if you want.

AS3GIF is a ActionScript library that lets you play and encode animated GIF’s with ActionScript 3.  Here is a piece of code to a sample Flex project that uses AS3GIF to display a Gif Image.

Other things that can be done with this library

You can code for shapes in ActionScript in a framewise sequence and encode them and play them as an image using GIFEncoder class in this library

Usability Perspective

This library is fine, it precisely solves the problem it has taken up to address, but my question is this – How many people actually use Gif Images in Flex applications? IF they do, do they use it as control components’ skins? or as background images? I’m not quite sure.

And oh! Here is the link to the sample project – download the code and copy paste all the files into a FlexBuilder/FlashBuilder project’s source folder – https://github.com/vatsala/FlexGif

Speaker and Topic
1) Balaji Damodaran of Thoughtworks- Windows Phone 7 internals and a bit of android
2) Siddharta Govindaraj of SilverStripe Software- Building Mobile apps using HTML(HTML5)/CSS
3)Gaurav Oberoi of Seattle Tech Startups – Web Sockets

Meeting Time: 10 AM

Venue: ThoughtWorks Technologies RR Tower 5 Level 2, Rishabh Info Park 33 A Developed Plots Thiru Vi Ka Industrial Estate Ekkatuthangal, Guindy Chennai – 600 032, India

You dont have to pay any money to come to the meet. But your interest in these topics is definitely a criteria for joining in.

Be there!

Finally here it is – There are a lot of tech events that are shaping up in Chennai – and I found it next to impossible to track any of them beyond a point.  So here is a compilation of as many events that I have tried to track in the past few days – I’ve setup a public Google Calendar for now. Its not very sophisticated, but good enough for now.

You can track/bookmark it from here http://vatsala.co.in/events.html as well

Alternatively You can catch the RSS feed here http://www.google.com/calendar/feeds/c6kgpqss1v04bd10ct7t9fago8%40group.calendar.google.com/public/basic

I’m wondering how to make this publicly editable – but thats for later. Siddharta Govindaraj’s idea sounds good – needs to be explored – http://siddhi.blogspot.com/2008/03/tracking-upcoming-community-techstartup.html

WordPress.com doesnt allow me to paste the Calendar inside the post(its an <iframe> tag) – So you will have check it out at the links above )

Here is an old article by Alex Harui - http://blogs.adobe.com/aharui/2007/03/thinking_about_item_renderers_1.html

A TechMeet is going to happen this saturday – The goal of the techmeet is to discuss and learn new trends,technologies,programming languages,new DBs, virtually anything thats new in the software programming world.
Here are the details:

When

Saturday 16th Oct – 10am onwards (2 to 2.5 hours)

Where

At Thoughtworks Chennai Office

RR Tower 5, Level 2, Rishabh Info Park, 33 A Developed Plots, Thiru Vi Ka Industrial Estate, Ekkatuthangal, Guindy
Chennai, Tamil Nadu 600032
044 4395 3500

What are the topics:

Building Applications using  Cloud Computing Platforms by  OrangeScape Tech Team (http://www.orangescape.com/)

MongoDB – A NoSQL database by Vagmi Mudumbai (http://blog.vagmim.com)

How can you help.

1. Please let us know whether you will be coming

2. Please spread the word (hashtag #techmeets)

3. Please add your questions on either (or both) topics at:

http://bit.ly/tmc-cctalk

http://bit.ly/tmc-nstalk

No registration required. You can just show up. But knowing how many people will be there will help us in terms of logistics. You can write to dorait[at]imorph[dot]com for any other questions that you may have.

It is very easy to setup a project that runs on Hibernate with the help of the multitude of beginner tutorials that come up on google search.  And the settings and steps described there are good enough to carry you through your development schedule.  But rememeber your hibernate settings are not production ready, i.e. not fit to be used on a machine that will stay turned on 24X7 and run your application in its Webserver container.

The problem you will face is this – You will deploy the application , and it will work smoothly. But shortly after a few hours, the DB will get disconnected with the following exception – detailed exception details here - http://pastebin.com/4KujAmgD

Hibernate Settings to be used to overcome the Communications Link Error are these

BUT, if you use these settings, and deploy your app, It will surely not work. Particularly if you use Hibernate 3.  You have to do one more step -

Download the latest c3p0 tar.gz file from http://sourceforge.net/projects/c3p0/ Now put the c3p0-0.9.1.x.jar file into your Webcontents/WEB-INF folder.

Now when you deploy your application, it will work without failing. For explanations about what the above settings mean, refer to http://www.skill-guru.com/blog/2009/10/06/hibernate-tutorial-part-ii/

And here are some initial findings – There are not any significant libraries for BDD in Flex.

For a focussed Java only app, there are a few options. Here is a discussion about this – http://stackoverflow.com/questions/1068785/which-bdd-framework-for-java-do-you-use

1)Jakarta Cactus – Extends JUnit and adds a few features

2)Cucumber – Originally written in Ruby, then got ported on to JRuby

3)JBehave – http://jbehave.org

4)JDave – http://www.jdave.org

These are the ones I have found so far, have to take each of them for a spin.