Thursday, April 20, 2006

First Experience with Ruby

It seems Ruby is becoming omnipresent these days. A lot of hype, hope and buzz seems to surround it. A few of my friends moved into ruby and went ooh-aah over the new fanged toy that does wonders. But when i tried to get them tell me what was so intersting and powerful, the common answer i got was that it was so simple to write code. Sufficiently piqued i decided to get some first hand experience.

So i borrowed a PragmaticProgrammer book on Ruby (online version can be found here) and started reading thru it. It is a good book with the only grouse being some of the topics were not covered in depth as i would have preferred.

Anyways after poring through half the book the list of features that spring out are

1. Fully OO

Everything seems to be a method connected to an object including new, loops etc. For e.g. to create a new instance of my object you do Numbers (java equivalent of int's) are all instances of FixedNum class so you can do things like 3.times, 3.step(30, 3). Both the 3.X methods are looping structures with the first one looping 3 times and the second behaving like a java for loop.

2. Iterators and Blocks

Ruby defines a bunch of iterators that operate over Ruby containers (Arrays, lists and hashes). Coming from the java world, to me an iterator just meant a way to loop through the contents of a collection. But Ruby iterator is a different beast that no only loops through the contents but also executes a 'Block' of code for each object in the collection. To make it seem less daunting, lets look at an example..

[ 1,2,3,4,5 ].each {|i| print i } This would print 1 2 3 4 5 on the console.

In Java, we'd have to do..

int numArr[] = {1,2,3,4,5}
for ( int i =0; i < style="font-weight: bold;">3. Closures

A closure is a block of code that retains the values of the instance/local variables it accesses or uses. So we can create a closure, which accesses a few local variables defined and set above it. This closure when passed to a method in a different class will retain the local variable values as it was in the original context.

Martin Fowler has a very good article on closures. Read it to know abt the power of closures.

4. Assignments and Operator Overloading

Assignments can be chained since each assignment returns that value as the result of the assignment expression. So doing a = (b = 1 + 2) + 3 will set a to 6 and b to 3. Also both if and case return the value of the last expression executed. so we can do i = if (num <>

Also operator overloading is supported. Damn java seems to be the only one not supporting it these days.

5. Getter/Setter

We can have getters/setters for object variables without writing methods. In ruby classes attr_reader and attr_writer followed by variable names will make the attributes readable/writeable.

6. Mixins

Ruby like Java supports only single inheritance. Mixin is a powerful concept where you define multiple modules and when u include them in your class all the methods in the mixins are accessible in your class. This mixin does not copy the code into the local class just references it, so any change to the module methods/variables in any class will affect globally.

For e.g. ruby comes with a standard module Comparable which defines comparision operators. For comparable to work we have to have implemented the method <=> in our class which the module uses. This is similar to an abstract base class in java but only we are allowed to have multiple abstract base classes for a single class. Pretty powerful !!

So Ruby has some features i like (all the ones above) but its arrays and collections are not strongly typed and i have a general aversion to such things having some bad memories from a VB/ASP project long ago.

Overall i have to think about some real life problems that ruby makes it easy to solve and actually scales well before actually going nuts over it.

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ravisk said...

It is nice to see you join the Ruby club. But remember that most of the developers moved to Ruby not just because the syntax is intuitive, the language has very powerful features like closures,continuations to name some. Are you aware that the full stack framework RoR (Ruby on Rails) is written within 2000 LOC.

Madhu said...

Even though Ruby makes programmers life simple ( if i can put it so ), but i have a strong feeling that ruby is more suited for Web Appln than any other complex multi tier J2EE appln.

More over, I think that it does not provide the user the chance to choose the framework more suited for the appln in different tiers as other Frameworks(such as Spring for Java) allows

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