Dhruva Sagar

Embrace the Wobble

Wed, 14 Jan 2026 20:45:12 +0530

Watching my daughter grip her bike’s handlebars for the first time, I saw the familiar flicker of fear in her eyes, the apprehension of the unknown, the hesitation to stumble, the dread of failure. It reminded me of a feeling I know too well, one that lingers in moments of uncertainty throughout our lives.

“What if I fall?” she asked.

I met her gaze and smiled. “Don’t be afraid of falling; instead be afraid of never falling,” I said.

Building a Scalable Ingestion Pipeline With Rust

Mon, 05 May 2025 16:58:25 +0530

How to build a scalable ingestion pipeline with Rust

Positive Effects of Exercise on Mental Health

Mon, 18 Nov 2024 10:51:28 +0530

Exercise is also a form of meditation, has tremendous positive impact on mental health

Neovim as a Java IDE

Sun, 01 Sep 2024 04:16:00 +0530

Neovim has come a long way today from it’s original goal of being able to support asynchronous jobs. Today it comes packed with a ton of useful and high performance libraries and plugins. To add to that it also has a highly enthusiastic and vibrant community of lua developers who are working tirelessly to make neovim better.

Today we’ll look at how one can easily configure neovim to work similar to a modern Java IDE.

How to Speak

Sun, 17 Mar 2024 19:54:06 +0530

Collection of my notes from the lecture titled ‘How to Speak’ by Patrick Winston

Generic Callbacks in Rust

Mon, 11 Mar 2024 10:45:06 +0530

In a recent project, we developed an ingestion pipeline in Rust. We wanted to execute asynchronous tasks in response to messages received from SQS, as a subscriber. Our goal was to leverage Rust generics to allow the subscriber to take ownership of the payload schema and the pipeline implementation details. This approach enables the separation of the SQS subscription logic from the subscriber’s responsibilities, promoting of cleaner separation of concerns. It also facilitates independent testing of both components, ensuring they can be assessed in isolation.

DIY remote controlled pan & tilt CCTV using Raspberry Pi

Fri, 06 Jul 2018 16:59:10 +0000

RPi CCTV in Action :

A simple web interface to control the RPi CCTV :

What you need to build this (hardware) :

Raspberry Pi(1) (1)Preferably Raspberry Pi-3, for on-board wireless, or Raspberry Pi Zero W, although you can achieve similar result without much effort using other boards
Pan & Tilt frame, I used one available here on amazon : https://www.amazon.in/gp/product/B010M25JVU/
2 servo motors. I used sg90 micro servo motors since I had them handy, however you can also use other similar ones available

I have recently started learning GoLang, and I decided to try to make use of it for a small IOT project that I’ve been meaning to do for a long time. In my research I came across Gobot, which is a framework for building robots written in golang. It comes with support for a lot of development boards available in the market such as Raspberry Pi, Beaglebone, Arduino, and several more. Not only that it also has drivers available for a wide variety of devices which can be used to create all sorts of nifty robots.

SSH Config Trick

Fri, 06 Oct 2017 19:21:20 +0000

Update2 : As I have been informed now, there has recently been support added for including external files in the ssh config. Refer https://man.openbsd.org/ssh_config#Include for details.

Update : Modified the script for more flexibility to allow easy modifications

I use SSH nearly every day to securely connect to remote servers. For simplifying managing remote server configurations & not having to remember IP addresses and other server specific details, I use ssh config. For those who aren’t familiar with this should read – http://nerderati.com/2011/03/17/simplify-your-life-with-an-ssh-config-file/

Text Editor Choice & Peer Pressure

Wed, 01 Mar 2017 10:37:42 +0000

I am a VIM user and have been for quite a long time(1) (1)~7 years . I am both a vim plugin author and also like to believe I have helped a lot of people switch / grok the core philosophy that I believe distinguishes it from all other editors and gives it an edge (IMO).

However, in this article I am not here to convince you to choose VIM as your choice of text editor, on the contrary, I am going to suggest you to do the opposite, especially if the only motivation to do so is driven by some form of peer pressure.

Template with Context using ERB

Wed, 01 Feb 2017 12:15:49 +0000

Recently, I was required to build a template rendering component that should render within a dynamic context, i.e. it would have methods / variables defined within a predefined context available during rendering, apart from what was provided directly.

For simplicity we chose ERB, since we can place them within locale files for internationalisation and designers could edit them with ease if need arises.

Following is a very simple implementation. Since we extend OpenStruct we can simply pass a hash to it during instantiation and all the keys will be accessible as methods and will be exposed directly during rendering.

Slack old school style

Sun, 13 Nov 2016 12:27:39 +0000

Slack has gained a lot of popularity in recent times as a tool for inter-team communication and for the right reasons. It offers a lot of features such as 3rd party software integrations, rich content communication, collaboration, bots etc. which when put together help create a rich collaborative user experience for teams to work together, especially when they are not co-located, which is fairly common these days.

If you’re anything like me and have been around long enough to know what IRC is and when you look at various elements that slack provides like channels, accounts (servers), private messaging, etc. you know that it draws a lot of parallels and inspiration from that old school communication tool.

WebRTC Broadcast

Wed, 02 Nov 2016 12:52:30 +0000

WebRTC is fun! I recently gave a quick session on WebRTC at Bangalore Ruby User Group (BRUG). Following are the slides of my presentation.

WebRTC from Dhruva Sagar

For demo I had recently created a demo application in elixir using the phoenix framework because it makes dealing with websockets really easy. That is used for creating the custom signaling service that is required to facilitate such a broadcast. The source code is available at dhruvasagar/webrtc-broadcast

Pristine – ZSH Theme

Sat, 28 Nov 2015 06:24:13 +0000

A while back I posted about Amuse my prompt theme for ZSH targeting oh-my-zsh. Since this was a much appreciated theme, I would like to share another theme, Pristine, that I have created.

However, I recently switched to using Prezto. This is because it felt like a more minimalistic configuration framework for ZSH. I also wanted to get faster load times. I must say my experience has been quite good and I really like it. Obviously there are pros and cons but I digress.

Google open sources it’s machine learning system

Mon, 09 Nov 2015 19:46:28 +0000

I am a huge proponent of open source technologies and having worked predominantly in various web technologies in the course of my career, I mostly work exclusively with open source stacks.

In the recent past I have been very keen to try and wrap my head around Artificial Intelligence and more specifically Machine Learning, although I am still barely even scratching the surface of the nitty-gritty’s of the field, especially the mathematical underpinnings, this is still a huge deal!

Grow your brain!

Mon, 09 Nov 2015 14:27:20 +0000

Learning is key in brain development. Of course what aspects and how much of brain function improve as a result depends on the mode / type / content & method of learning. But I am not here to talk about that. Now, this knowledge isn’t new information, we all know this already, and have seen it in good effect in children and hence we all know and understand the importance of education & sport for children.

Find huge files in linux

Fri, 08 May 2015 04:17:01 +0000

Switching to SSD’s for better performance and compromising on disk space can be a tough decision to make. Though nowadays with the prices of SSD’s going down, it is something that a lot of people are consciously doing.

However having spoilt by past experiences of having ample disk space when you switch from a 500GB (or 1TB) hard disk to an, albeit super fast, 128GB SSD, you will inevitably run into situations where you need to clean out large files taking space on your disk. Something I had run into myself about a year back when I made the switch myself on my macbook. Oddly enough this problem turned out to be significant enough that I had to seek out a way to quickly find out which were the top biggest files on my file system so I could get rid of them / move to an external hard disk.

Google Code Jam 2014 Qualifiers

Mon, 14 Apr 2014 08:55:35 +0000

Google Code Jam has always been a competition I have cherished, simply because the problems they post are brilliant and the closest to reality as compared to problems of other competitions. They’re always fun to read, disect & solve, more often than not, the solutions are reasonably trivial(1) (1)Especially for the qualifiers yet extremely subtle & deceptive.

Today I want to share the solutions of 3 problems I was able to solve, the code should pretty much speak for itself because none of it is very complex.

VIM Custom TabLine

Sat, 05 Apr 2014 18:40:01 +0000

Hi guys,

VIM has an option tabline that one can use to configure how the tab line would look like. Back when I used to use gvim, I could very easily manipulate how the text on the tab looked like by setting the guitablabel setting, however tabline is not all that easy to configure.

Here is what I use now :

function! MyTabLine()
  let s = ''
  for i in range(tabpagenr('$'))
    let tabnr = i + 1 " range() starts at 0
    let winnr = tabpagewinnr(tabnr)
    let buflist = tabpagebuflist(tabnr)
    let bufnr = buflist[winnr - 1]
    let bufname = fnamemodify(bufname(bufnr), ':t')

    let s .= '%' . tabnr . 'T'
    let s .= (tabnr == tabpagenr() ? '%#TabLineSel#' : '%#TabLine#')
    let s .= ' ' . tabnr

    let n = tabpagewinnr(tabnr,'$')
    if n > 1 | let s .= ':' . n | endif

    let s .= empty(bufname) ? ' [No Name] ' : ' ' . bufname . ' '

    let bufmodified = getbufvar(bufnr, "&mod")
    if bufmodified | let s .= '+ ' | endif
  endfor
  let s .= '%#TabLineFill#'
  return s
endfunction
set tabline=%!MyTabLine()

This is what it looks like :

Creating Custom Scratch Buffers in VIM

Tue, 11 Mar 2014 09:07:22 +0000

The other day I wanted to open a scratch buffer to write some temporary code and the pass it on to a repl to test it out, the idea was that I could modify it as needed and resend it back to the repl and see the changes, helps to debug easily.

So I just wrote out this simple code here that allows me to launch a scratch buffer in different ways, but the difference is I can set various options for it while creating it. First lets have a look at the code :

VIM – Filter Quickfix List

Tue, 17 Dec 2013 10:15:07 +0000

If you are used to using the quickfix list in VIM there are times when you want to filter certain things out of the quickfix list to narrow it down to relevant results that you need. Rather than firing the quickfix command all over again with a refined expression, it is easier & often faster to simply remove items from the list. I wrote this simple vimscript to do just that.

VIM – Toggle Ruby Hash Syntax

Tue, 26 Nov 2013 15:05:55 +0000

Ruby 1.9 introduced a new json style ruby hash syntax. Although we can use this to define static hash objects and puts a limitation on the key we can use, it’s a fairly neat syntax nevertheless. However I work on several projects, both new and old and hence the new syntax is not always readily available.

# Old style hash
hash = { :a => 'test' }

# New style hash
hash = { a: 'test' }

To demonstrate the sheer power of regular expressions & VIM, here’s a tiny snippet that allows you to quickly toggle a ruby hash syntax from one form to other.

VIM for Multiple Projects in separate Tmux windows

Tue, 26 Nov 2013 05:20:57 +0000

My development environment setup consists of several tools, however the 2 most used and essential tools that have a great impact on my workflow are tmux & vim. Since I often work on several projects, I find it best to work on different vim sessions in separate tmux windows.

However tmux by default only shows the name of the currently running process in the title and that can often lead to confusion as to which tmux window is which project. To solve this issue I came up with a very simple vim script that utilizes tmux’s powerful API to automatically rename the tmux window appropriately and hence make it incredibly easy for me to know which tmux window is for which project.

ActiveRecord like where for array of hashes in ruby

Sat, 20 Apr 2013 05:36:35 +0000

Edit : Updated the code as per the suggestions made by Masklinn.

Recently I was working on Issue#1 of my Soulmate Rails gem, which is a very simple and obvious optimization that I should have thought of myself. Thanks to lephyrius though for pointing it out. In my search method I was looping through the search results and calling find on each to get it from db. The fix involved to instead use a single where for all ids so that it translates to a single db call. A simple fix as well as an optimization.

VIM Markify

Mon, 01 Apr 2013 13:06:29 +0000

Recently I picked up some minor configs for ruby from Time Pope’s vimrc. Here’s the code :

autocmd FileType ruby
    \ if expand('%') =~# '_test\.rb$' |
    \   compiler rubyunit | setl makeprg=testrb\ \"%:p\" |
    \ elseif expand('%') =~# '_spec\.rb$' |
    \   compiler rspec | setl makeprg=rspec\ \"%:p\" |
    \ else |
    \   compiler ruby | setl makeprg=ruby\ -wc\ \"%:p\" |
    \ endif

What this does is given the filetype is Ruby, it correctly sets up the compiler and makeprg such that it allows you to run your tests via :make! This is pretty neat I must say :), because it correctly loads the quickfix list with the errors and I can actually traverse them in order and fix them. All this without needing any plugin whatsoever :).

VIM Better FoldText

Thu, 28 Mar 2013 18:00:54 +0000

Update 3: Improved the code for extraction of fillchar from fillchars option and taking foldcolumn into account.

Update 2: Fixed the regex for removing the fold marker from the displayed text by splitting the '{{{' in the regex to '{{'. '{' so that it is not treated as a fold marker by vim. Thanks to Amadan on reddit Reddit Tip

Update: Fixed NeatFoldText() to get foldchar from fillchars settings.

Initially when I started using VIM, I had borrowed configs from my mentor Vagmi Mudumbai (1) (1)To whom I am Eternally Thankful!!! .

VIM Table Mode

Sun, 17 Mar 2013 07:20:15 +0000

UPDATE 2: Released v 2.0 of the plugin. Check github for details.

UPDATE : I have added more features to the original plugin, showcasing some core features in a new demo (Part 2).

Recently a friend of mine showed off emacs table mode to me and to be honest, I felt a bit jealous :). Hence I began to search for existing vim plugins that might offer a similar functionality and I did find a plugin VIM RST Tables, which is a ftplugin that aids the creation of tables within rst files and allows you to format existing content into a table, although this plugin came closest to what I was looking for it wasn’t quite there. Then I found a very interesting & simple plugin shared as a gist by the infamous Tim Pope: cucumbertables.vim which I found quite impressive.

Amuse – ZSH Theme

Wed, 13 Mar 2013 11:12:50 +0000

Amuse is a simplistic theme I built for the popular shell ZSH that I use.

Features :

Shows git prompt with additional support for dirty (! in red) and untracked (? in green) git flags.
Shows the system time with a neat time unicode character. Although I am sure most wouldn’t find having time on the prompt useful, I find it very useful since it helps me get a good idea on how long a command took to execute or even how long back I executed some command. Check the screenshot for reference.
Prompt where you type the command starts after a $ on a new line giving you ample space (full width barring the $ and a space) to type your command and so the prompt (especially if it’s long, eg. if you are in some deep nested directory) does not interfere with your commands and avoids wrapping for the most part unless you are typing an excessively long command in which case you should probably use an editor (VIM) to edit it with ^X^E .
Shows you the current ruby version in use from rvm, using the rvm current command in the right prompt. The ZSH right prompt is really cool and since I use rvm with several ruby versions which change with different projects .rvmrc files, the right prompt helps me to know the ruby context at all times. It shows the full ruby version along with the gemset name in use. The nice thing about the right prompt in ZSH is that it hides automatically if you happen to type a command that’s long enough to reach it :).

UPDATE: My AMUSE theme for Oh My Zsh was merged into the repository so you don’t need my fork anymore which has since been deleted.

Vim Railscasts Colorscheme

Fri, 08 Mar 2013 08:03:00 +0000

VIM in my muscle memory is one of my popular posts, the day I published it, I attracted over 3,200 unique views in a single day, mostly from Hacker News and Reddit Programming. Although it is an extremely densely packed post with lots of information, I hope it has helped some to appreciate VIM like I do.

In my several years of VIM usage, I have tried several colorscheme’s, though I have come to like only a select few. One colorscheme that I have liked the most and have always ended up coming back to is the Railscasts theme. There are 2 versions of this script :

Soulmate Rails

Mon, 04 Mar 2013 08:11:28 +0000

UPDATE : I released the first stable version 0.2.1, it should be usable as is without any issues.

One of the most common things to do in any standard rails web applications is auto-completion. One interesting solution for this is by using redis’ sorted sets (1) (1)Which are blazing fast , storing key value pairs for partial matches. For example, if we wish to index the word ‘Dhruva Sagar’, you can simply create key -> value pairs of ‘d’ -> ‘Dhruva Sagar’, ‘dh’ -> ‘Dhruva Sagar’, ‘dhr’ -> ‘Dhruva Sagar’ and so on. Since hash lookups are of constant time complexity O(1), they’re very fast and hence the completions are too! Combine this with using sorted sets of redis to easily order / sort information on a specific criteria and you have a blazing fast solution. Of course the actual implementation can be further optimized by means of caching query results and make the system perform even further.

Tmux Powerline Special Characters Issue

Sat, 23 Feb 2013 07:16:45 +0000

Tmux is a terminal multiplexer like Screen on steroids. It is faster, slicker and much more easily extendable than screen. For why you might want to try tmux over screen checkout these articles :

Tmux Powerline is an extension to tmux’s statusline which makes it look incredibly cool. Look at this screenshot:

Tmux Powerline.

There are 2 projects that provide this feature.

Ubuntu on Macbook Pro

Fri, 28 Dec 2012 11:02:32 +0000

As I have mentioned before ([Magician Chrome makes RAM disappear][1]), I had been facing several issues with Mac OSX. I use vim extensively, and so I had installed MacVim(1) (1)after great difficulty on my Macbook Pro, but recently while trying out a new plugin I found there was something amiss between MacVim & Python on my system and as a result I was unable to use the plugin. In my attempt at trying to repair MacVim, I ended up uninstalling it.

Magician Chrome makes RAM disappear

Tue, 28 Aug 2012 08:47:19 +0000

Recently I have been experiencing a very weird issue on my Macbook Pro, I have Lion v10.7.4, with a decent configuration : 2.8 GHz Intel Core i7 processor, 8GB Ram with a 750GB sata hard disk. But over a reasonably prolonged period of usage, of around 4-6 hours, I notice from time to time that Mac OSX runs completely out of RAM! The Activity Monitor reports mere MBs of Free Memory, sometimes even less than 10MB. Needless to say this makes the Macbook loose it’s mind, it would freeze up on random, seemingly basic tasks, even switching to a window can freeze the macbook for minutes, if not hours. Which is understandable, though, given how low memory it is left with.

VIM in my muscle memory

Fri, 24 Aug 2012 17:59:45 +0000

I have been an ardent VIM user for almost 4 years now, and it’s been a while since I have been wanting to write this Blog. My motivation is not to showoff or to start any flame war against any other popular text editors that may or may not be better ;), but to simply showcase the things I like and have come to appreciate in VIM, and show why you should seriously consider it when deciding which programming editor you should use. Hopefully I will be able to do justice to VIM - the Ultimate Programmer’s Editor.

Artificially Intelligent Spyware

Tue, 21 Aug 2012 09:58:49 +0000

There has been tremendous advancement in the domain of Artificial Intelligence (AI) and Machine Learning (ML) in the recent years. Although people often like to take a shot at the state of AI on the grounds of the fact that several of the early claims on AI that it will soon become almost as real as humans haven’t really materialized, there still has been an incredible amount of growth in this domain.

Getting started with Ruby – TOC

Fri, 24 Dec 2010 18:29:47 +0000

Hi,

I have written a series of articles (in several parts) in an attempt to guide beginners to get comfortable with Ruby. This article is my attempt to build a TOC (Table of Contents) for it to act as an index for people to get a brief idea regarding what each article is about and help them get to the sections they are interested in.

Getting started with Ruby - Part 1: In this article I begin with an introduction to myself and my motivation behind writing these articles. I give an introduction to Ruby, about how to get started with building your development environment and introduce a few tools that ship along with Ruby which will make your life that much better.
Getting started with Ruby - Part 2: In this article I introduce Ruby in slightly more detail and I get started with describing different data types in Ruby. I cover Strings and Numbers in this article.
Getting started with Ruby - Part 3: In this article I continue from my previous article describing data types in Ruby and cover Ranges and Arrays.
Getting started with Ruby - Part 4: In this article I continue further and cover Hashes, one of the most commonly used data types in Ruby. I also introduce blocks and about using blocks with functions.
Getting started with Ruby - Part 5: In this article I move onto describing various looping constructs in Ruby, and also various flow control modifiers in Ruby. After that I introduce Variables, Symbols, Constants, Methods and Global Variables in Ruby.
Getting started with Ruby - Part 6: After having covered basics of various constructs in Ruby, I considered it better to take a problem statement and solve it in Ruby to bring most of what we’ve discussed into use. I chose Google Codejam 2009′s qualification round problem – Alien Language

I tried to be clear, precise and specific. My intention was write more code than to waste time in trying to explain and so I’ve used code comments to help people understand what each part of the code is meant to do. I have plans on going further and go onto describing classes & modules, sometime soon, even though I expected more people to read and give their feedback, but owing to a lot of work and hence a lack of time, I haven’t been able to do much justice to the same, but hopefully I will be able to do so very soon. I hope it helps people appreciate Ruby and motivate them to learn and understand it.

MongoMapper Plugin – Versionable

Thu, 02 Dec 2010 03:53:38 +0000

There was a requirement at one of our projects here at Artha42 Innovations Private Limited that our Mongo Mapper documents have inherent versioning so as to be able to track the changes being made and also if required revert the changes to a previous state. Since we’re using MongoMapper, I set out to create a simple plugin for the same to add the required functionality.

Initially, from the initial research I did, I found Shapado had an implementation of exactly what I wanted, however when I studied and understood their implementation in detail, I realized that it doesn’t really work that well in most scenarios, especially the ones we were tackling in our project. Shapado’s versionable allows you to define a set of keys for a document, whose changes would trigger creation of new versions. However in our project we needed to track changes at the complete document level, i.e. even for changes in the associations. Also the versions were embedded within the document itself, which implied that the document would grow in size very rapidly, even though our changes in each iteration could be minor, since each version would literally be a snapshot of the complete document itself.

Calculating Hashes

Thu, 25 Nov 2010 09:30:27 +0000

Showcasing how to calculate hashes in Java, C# and Ruby!

Java : #

public String getHash(String message, String algorithm) {
    try {
        byte[] buffer = message.getBytes();
        MessageDigest md = MessageDigest.getInstance(algorithm);
        md.update(buffer);
        byte[] digest = md.digest();
        String hexValue = null;
        for(int i = 0 ; i &lt; digest.length ; i++) {
            int b = digest[i] & 0xff;
            if (Integer.toHexString(b).length() == 1) hex = hex + "0";
            hex  = hex + Integer.toHexString(b);
        }
        return hex;
    } catch(NoSuchAlgorithmException e) {
        e.printStackTrace();
    }
    return null;
}

C# : #

using System;
using System.Text;
using System.Security.Cryptography;

public String getHash(String message, String algo) {
    byte[] sourceBytes = Encoding.Default.GetBytes(message);
    byte[] hashBytes = null;
    Console.WriteLine(algo);
    switch(algo.Trim().ToUpper()) {
        case "MD5":
            hashBytes = MD5CryptoServiceProvider.Create().ComputeHash(sourceBytes);
            break;
        case "SHA1":
            hashBytes = SHA1Managed.Create().ComputeHash(sourceBytes);
            break;
        case "SHA256":
            hashBytes = SHA256Managed.Create().ComputeHash(sourceBytes);
            break;
        case "SHA384":
            hashBytes = SHA384Managed.Create().ComputeHash(sourceBytes);
            break;
        case "SHA512":
            hashBytes = SHA512Managed.Create().ComputeHash(sourceBytes);
            break;
        default:
            break;
    }
    StringBuilder sb = new StringBuilder();
    for(int i = 0 ; hashBytes != null && i &lt; hashBytes.Length ; i++) {
        sb.AppendFormat("{0:x2}", hashBytes[i]);
    }
    return sb.ToString();
}

Ruby : #

require 'digest'

def getHash(message, algo='md5')
  case algo.strip.upcase
  when "MD5" then Digest::MD5.hexdigest(message)
  when "SHA1" then Digest::SHA1.hexdigest(message)
  when "SHA256" then Digest::SHA256.hexdigest(message)
  when "SHA384" then Digest::SHA384.hexdigest(message)
  when "SHA512" then Digest::SHA512.hexdigest(message)
  end
end

As you can see, the Ruby version to calculate hashes is the most concise & simple.

Getting started with Ruby – Part 6

Wed, 03 Nov 2010 04:22:09 +0000

After having covered most of the basics of Ruby, lets get started on an actual problem, just like I had promised in my previous article – Getting started with Ruby – Part 5

I am taking a relatively simple problem that came in Google Codejam 2009 qualification round. Here is the direct link to the problem : Alien Language

After years of study, scientists at Google Labs have discovered an alien language transmitted from a faraway planet. The alien language is very unique in that every word consists of exactly L lowercase letters. Also, there are exactly D words in this language.

Getting started with Ruby – Part 5

Tue, 26 Oct 2010 03:35:06 +0000

Hi in my previous article Getting started with Ruby – Part 4 I covered Hashes & blocks.

Today I will take you through the various forms of loops in Ruby.

While #

Executes code as long as the given condition is true. We can separate the code from the condition using either the keyword do, a newline or a semi-colon (;)

i = 0
while i > 5 do
    puts "Iteration #{i}"
    i += 1
end
# Output :
# Iteration 0
# Iteration 1
# Iteration 2
# Iteration 3
# Iteration 4
# Alternatively, it is also possible to use the while loop as a modifier
# towards the end of a statement or a code block
i = 0
begin
    puts "Iteration #{i}"
    i += 1
end while i > 5
# Output :
# Iteration 0
# Iteration 1
# Iteration 2
# Iteration 3
# Iteration 4

Until #

Is very similar to the while loop with respect to the syntax & usage, the only difference between the two is the fact that the while loop executes the code block as long as the condition is true, the until loop does exactly the opposite, i.e. it executes the code block as long as the condition is false.

Getting started with Ruby – Part 4 – Hashes & Blocks

Fri, 22 Oct 2010 19:57:01 +0000

In my previous article Getting started with Ruby – Part 3 I started with Collections and covered basics of Ranges & Arrays. Like I mentioned towards the end of the article (in case you couldn’t manage to reach the end) I will start with one of the most commonly used Collection objects in Ruby, namely Hashes.

Hashes are essentially data structures to store key – value pairs, when you wish to store an element in the Hash you do so by assigning a unique key to it within the hash and while retrieving you do so with the help of that unique key. The beauty of hashes is the fact that the ‘key’ in question here could be just about any object in Ruby, most commonly however in practice strings or symbols (i’ll get to what these are soon) are used as keys.

Getting started with Ruby – Part 3 – Collections, Ranges & Arrays

Wed, 20 Oct 2010 19:27:19 +0000

In my previous article Getting started with Ruby – Part 2 I introduced you all to Ruby & its philosophy and I started out with data type classes in Ruby. I was able to give you an overview about Strings & Numbers in ruby. Today I will start with Collections.

The Range #

As the name suggests, ranges hold a sequential collection of numbers. Defining a range in Ruby is extremely simple, instead of explaining, i’ll show it to you. Don’t be afraid to start an IRB shell to try the code out.

Getting started with Ruby – Part 2 – Introduction & Philosophy

Mon, 18 Oct 2010 18:53:29 +0000

Hi again, this is part 2 of my series of articles to help beginners getting started with the Ruby programming language. At this point of time I would like to quote the definition of Ruby from the Ruby Programming Language:

A dynamic, open source programming language with a focus on simplicity and productivity. It has an elegant syntax that is natural to read and easy to write.

I know I had already quoted Ruby’s definition from wikipedia in my previous article Getting started with Ruby - Part 1, but that was more from a technical standpoint. Here I wanted to draw your attention to Yukihiro Matsumoto‘s(1) (1)Popularly known as Matz philosophy behind creating Ruby, which is making programming as simple & natural as humanely possible. We will be witnessing that very soon.

Getting started with Ruby – Part 1

Mon, 18 Oct 2010 18:38:33 +0000

Before we get started with Ruby, let me first give you a brief on who I am, I am Dhruva Sagar, a software engineer having a little over 4 years of professional experience having worked in technologies in and around Java, Javascript, Adobe Flex, PHP and Ruby. I have always been fascinated by programming languages and have been eager to learn new ones and I can also code comfortably in Perl, Python & Groovy, however I haven’t worked extensively on these. Right now I am working in a startup Artha42 Innovations Private Limited and am having the best time of my life!

Moving to Ubuntu

Tue, 06 May 2008 09:59:31 +0000

I have worked on quite a few Linux distros, Redhat, Knoppix, BackTrack, PHLAK, ubuntu, etc. But most of the times I did that only to explore the realm of Linux and see for myself what its all about and explore a little more for the particular distro’s utilities, and not to actually shift myself completely to using it solely, since I have been accustomed to using windows and the various softwares that I use on windows.

Cleaning data on my computer

Mon, 05 May 2008 03:50:14 +0000

I remember my first computer which I had when I was in about 4th standard(1) (1)About 15 years back if I remember correctly . It was a real source of entertainment for me at the time. Although I did enjoy playing basic dos games on it for long durations a lot, but I remember that computer and most importantly it’s exact configuration because of a really hilarious incident that happened with me!(2) (2)Well considering my age at that time and my level of understanding of computers, it really was hilarious, not that dumb 😀

Calculating a MD5, SHA1, SHA256, SHA384, SHA512 Hash in C#

Wed, 15 Aug 2007 18:12:56 +0000

Following up on my Creating a Hash in Java post, here I am giving another implementation through a simple function for calculating a Hash in C#.

Here’s the code:

using System;
using System.Text;
using System.Security.Cryptography;

public String computeHash(String message, String algo) {
	byte[] sourceBytes = Encoding.Default.GetBytes(message);
	byte[] hashBytes = null;
	Console.WriteLine(algo);
	switch(algo.Trim().ToUpper()) {
		case "MD5":
			hashBytes = MD5CryptoServiceProvider.Create().ComputeHash(sourceBytes);
			break;
		case "SHA1":
			hashBytes = SHA1Managed.Create().ComputeHash(sourceBytes);
			break;
		case "SHA256":
			hashBytes = SHA256Managed.Create().ComputeHash(sourceBytes);
			break;
		case "SHA384":
			hashBytes = SHA384Managed.Create().ComputeHash(sourceBytes);
			break;
		case "SHA512":
			hashBytes = SHA512Managed.Create().ComputeHash(sourceBytes);
			break;
		default:
			break;
	}
	StringBuilder sb = new StringBuilder();
	for(int i = 0 ; hashBytes != null && i &lt; hashBytes.Length ; i++) {
		sb.AppendFormat("{0:x2}", hashBytes[i]);
	}
	return sb.ToString();
}

Calculating a MD5, SHA1, SHA256, SHA384, SHA512 Hash in Java

Mon, 13 Aug 2007 17:58:32 +0000

Hi, today I will show you with examples how to evaluate Hashes in Java programming language. I hope this information comes in useful for many people.

Java which is my favorite programming language because of sheer simplicity, vastness and ease with which you can customize and extend existing libraries to suit your needs.

/**
 * The getHash method returns the hash of the message
 *
 * @param message The message to be hashed
 * @param algorithm The hashing algorithm to be used,
 *                  Possible values are MD2, MD5, SHA-1, SHA-256, SHA-384, SHA-512
 *
 * @return The hash of the message
 *
 * @author Dhruva Sagar
 */
public String getHash(String message, String algorithm) {
  try {
    byte[] buffer = message.getBytes();
    MessageDigest md = MessageDigest.getInstance(algorithm);
    md.update(buffer);
    byte[] digest = md.digest();
    String hexValue = null;
    for(int i = 0 ; i &lt; digest.length ; i++) {
      int b = digest[i] & 0xff;
        if (Integer.toHexString(b).length() == 1) hex = hex + "0";
          hex  = hex + Integer.toHexString(b);
        }
      return hex;
    } catch(NoSuchAlgorithmException e) {
      e.printStackTrace();
    }
    return null;
}

About

Mon, 01 Jan 0001 00:00:00 +0000

I am Dhruva Sagar #

When I was 15 year old. My dream was very simple. I wanted to write code. Open Source code, more specifically. I have been chasing that dream for a long time(1) (1)~18 years professionally, significantly longer if you count the time since I was writing code in school / college . Still at it. That’s what keeps me going.

This site is my little corner of the web where I jot down some of the interesting things I come across

Now

Mon, 01 Jan 0001 00:00:00 +0000

What I am focused on NOW