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Convert Vi into a powerful Python IDE March 9, 2009

Posted by razasayed in Hacks, programming.
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Below is a simple two step recipe for converting Vi into a full fledged IDE for python . Though there are numerous powerful features which can be added to Vi, to make it more powerful as an IDE, for simplicity’s sake and also to enable newcomers to easily get started with using some of these great features, im gonna share a couple of ways in which you can use Vi as a Python IDE.

These tips would enable you to get all those cool features like code completion , syntax highlighting , automatic indentation in Vi which would definitely make you more productive as a python hacker.

Step 1) For automatic code completion, download the pydiction plugin for Vi, from http://www.vim.org/scripts/script.php?script_id=850

Then, you need to extract this file into  your .vim directory. Assuming its in your home directory e.g.) /home/raza/.vim (If .vim directory does not exist create it), you run the following command from the location where you dowloaded the plugin

tar xvzf pydiction-0.5.tar.gz -C ~/.vim

To use auto-completion, simply press Ctrl-n or Ctrl-p , while in Insert mode.

Step 2) Now, add the following piece of code to your .vimrc file. This file is located either in your home directory or in /etc/vim.
If you dont want to risk messing up your existing .vimrc, you can create a backup of it, and create a new .vimrc file and then paste the following code in it:

[Note:] Dont forget to replace /home/raza/.vim in the code below with the location of your .vim directory

set nocompatible
syntax on
set showmatch
set ignorecase
set showmode
set ts=4
set sw=4
set autoindent
set smartindent
set number
autocmd FileType python runtime! autoload/pythoncomplete.vim
imap <c-space> <c-x><c-o>
:set backspace=2
if has("autocmd")
        autocmd FileType python set complete+=k/home/raza/.vim/pydiction-0.5/pydiction isk+=.,(
        endif " has("autocmd"

filetype plugin on
filetype indent on

" Mappings
nmap <C-N> :noh <CR>

Thats all there is to it ! . If you want to directly execute your program , without having to leave vi, then switch to command mode and execute the following command:

:!python <yourfilename>.py

There are more cool features like adding support for snippets, debugging etc that can be added to Vi, but maybe ill cover them in a later post.
If readers would like to share any more tips for customizing Vi for python development, then you are welcome to post them in your comments.
Hope this makes your python programming more productive and fun.

Happy Hacking ! 🙂

Launch your program from within Notepad++ February 22, 2009

Posted by razasayed in programming.
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15 comments

Notepad++ is a good editor for programmers, that supports multiple languages, and also has some other cool features like syntax highlighting, some basic intellisense etc.. . It is free and open source , but the downside is that its available only for Windows . However, it does work on Linux too, by using Wine. Notepad++ is a good alternative for people (especially those using Windows,on Linux  vi or  emacs  are the commonly used editors) who for whatever reason are not using full fledged IDE’s , and want a simple editor with some of the bells and whistles required for their programming work.

Recently, i discovered a cool feature supported by Notepad++, which i thought id blog about . How many times have we encountered situations where we write code in an editor and then switch back to the command line to execute it , especially if we are dealing with interpreted languages like perl, python , ruby etc..

Wouldnt it be nice if we could execute the program within the editor itself  ?. Now that would come in really handy . Would definitely save us some time and overhead involved in the context switch 😉 .

Guess what, Notepad++ being plugin based , has a plugin called NppExec , which allows us to do just that .  All you have to do is download it (assuming this plugin is not already installed)  , then after extracting the archive, place the dll in <Notepad++ Installation directory>/plugins .

Heres how to use it (assuming you are using python , and have the python interpreter installed on your system , however it could be any other language for which you have the corresponding interpreter installed)

Step 1) First type in your program and save the file

Step 2) Go to Plugins->NppExec->Execute (or press F6), and in command section type


python "$(FULL_CURRENT_PATH)"

$(FULL_CURRENT_PATH) , is a Notepad++ internal variable ,that contains the full path of the file currently open in the editor . There is a list of 10 such global variables here

Step 3) Now click on Save, and type a name for this script, so that we can use it again later on.

Step 4) Press OK

Voila, you can now see the output of your program in a console window in the editor itself ! .

Then again when you make some changes to your code, you dont have to go through all the above steps again, simply press Ctrl+F6, which is the shortcut for repeating the previous command.  To switch to a different language you can press F6 and select any other language for which you have saved a script.

Tip : If you dont want those extra messages that you see along with the output, just select Plugins->NppExec->No Internal Messages

Hope someone finds this useful,

Have fun 🙂

Python programmers can fly :) January 10, 2009

Posted by razasayed in programming.
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Heres a nice one from xkcd :).

Master Foo and Unix December 25, 2008

Posted by razasayed in programming.
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The Unix operating system has been greatly influenced by the Zen philosophy . A “Koan” is a puzzling, often paradoxical statement or story, used in Zen Buddhism as an aid to meditation and a means of gaining spiritual awakening.The  Rootless Root has some wonderful unix koans which is a must read . These koans would help you find the way. And, if  you mock at them you’ll lose merit and be reborn as beasts or MCSE/MCSD/MCTS etc 😉 . Here are a couple of samples .

1. Master Foo and the Graphical User Interface

One evening, Master Foo and Nubi attended a gathering of programmers who had met to learn from each other. One of the programmers asked Nubi to what school he and his master belonged. Upon being told they were followers of the Great Way of Unix, the programmer grew scornful.
“The command-line tools of Unix are crude and backward”, he scoffed. “Modern, properly designed operating systems do everything through a graphical user interface”.
Master Foo said nothing, but pointed at the moon. A nearby dog began to bark at the master’s hand.
“I don’t understand you!” said the programmer.
Master Foo remained silent, and pointed at an image of the Buddha. Then he pointed at a window.
“What are you trying to tell me?” asked the programmer.
Master Foo pointed at the programmer’s head. Then he pointed at a rock.
“Why can’t you make yourself clear?” demanded the programmer.
Master Foo frowned thoughtfully, tapped the the programmer twice on the nose, and dropped him in a nearby trashcan.
As the programmer was attempting to extricate himself from the garbage, the dog wandered over and piddled on him.
At that moment, the programmer achieved enlightenment

Heres one more 🙂 . Master Foo and the Script Kiddie

A stranger from the land of Woot came to Master Foo as he was eating the morning meal with his students.
“I hear y00 are very l33t”, he said. “Pl33z teach m3 all y00 know”.
Master Foo’s students looked at each other, confused by the stranger’s barbarous language. Master Foo just smiled and replied: “You wish to learn the Way of Unix?”
“I want to b3 a wizard hax0r”, the stranger replied, “and 0wn ever3one’s b0xen”.
“I do not teach that Way”, replied Master Foo.
The stranger grew agitated. “D00d, y00 r nothing but a p0ser”, he said. “If y00 n00 anything, y00 wud t33ch m3”.
“There is a path”, said Master Foo, “that might bring you to wisdom”. The master scribbled an IP address on a piece of paper. “Cracking this box should pose you little difficulty, as its guardians are incompetent. Return and tell me what you find”.
The stranger bowed and left. Master Foo finished his meal.
Days passed, then months. The stranger was forgotten.
Years later, the stranger from the land of Woot returned.
“Damn you!” he said, “I cracked that box, and it was easy like you said. But I got busted by the FBI and thrown in jail”.
“Good”, said Master Foo. “You are ready for the next lesson”. He scribbled an IP address on another piece of paper and handed it to the stranger.
“Are you crazy?” the stranger yelled. “After what I’ve been through, I’m never going to break into a computer again!”
Master Foo smiled. “Here”, he said, “is the beginning of wisdom”.
On hearing this, the stranger was enlightened.

And finally for all the programmers out there, The Tao Of Programming is a must read !

Thus spake the master programmer:

“It is time for you to leave.”

Online C compiler November 22, 2008

Posted by razasayed in Hacks, programming.
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Sometime back i was at my friends place . He was preparing for some test and he showed me a complex looking C expression , and asked me what it would evaluate to . I told him what i thought would be the answer but anyways we needed to verify it .  He did not have a C compiler installed on his machine . But, luckily enough he did have an internet connection , and google came to the rescue .

There is an online C compiler available at http://www.delorie.com/djgpp/compile/ . It runs your program and gives the executable for download . Pretty cool and quite handy when we quickly need to check the output of some C program , but dont have access to a C compiler . Saves some time on downloading and installing one.

However, of course this wont work if you are using a GNU/Linux system, as the output is an exe . However, for those users gcc is just a synaptic away 😉

Code::Blocks, a good C/C++ IDE for Linux October 2, 2008

Posted by razasayed in programming.
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Just some time back my brother who was using a Linux machine, asked me how he could do C/C++ development on that platform . Most colleges here in Mumbai teach students how to use the Borlands Turbo C++ IDE, a.k.a TC which i think by now is pretty outdated and can well be classified as an antique piece of software . Also, its a Windows only program , and when it comes to C/C++ programming on “Windows” most students never look beyond “toy” programs like prime numbers, factorial, matrix operations etc and use Microsoft Visual Studio for doing GUI stuff.

I think Linux is a good platform for budding C/C++ developers to hack on , where C/C++ are still the main “programming” languages used by developers , in addition to “scripting” languages like Python , PHP etc..

While there are numerous alternatives for C/C++ programming on Linux as far as IDE’s are concerned , for example, Eclipse , Anjuta , KDevelop etc, Code::Blocks according to me appears to be a really easy to use and lightweight IDE . Also just like Eclipse, Code::Blocks is also plugin based, and supports a lot of cool features we expect out of IDE’s like integrated debugger ,syntax highlighting, code completion , class browsers etc..

To install Code::Blocks on my bros machine running Ubuntu i performed the following procedure :

Step 1) Code:Blocks requires the wxWidgets , a cross-platform C++ GUI toolkit to be installed, so first install that by issuing the following command at the terminal :


sudo apt-get install libwxgtk2.8-0

Step 2) Download the Code::Blocks binary for Ubuntu from http://www.codeblocks.org/downloads/binaries

Step 3) Unzip the archive. Now , you will get a set of deb files.

Step 4) Finally, run the following command to install :


sudo dpkg -i *.deb

Thats it . You should now see the icon for Code::Blocks in your Programming Menu.

Note : I was facing some issues while trying to build gtk+ programs in Code::Blocks v8.02 , inspite of having the libgtk1.2-dev package installed .  However, the problems were resolved once i installed the libgtk2.0-dev package .

Happy Hacking ! 🙂

The Zen Of Python August 22, 2008

Posted by razasayed in programming.
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Heres a list of 19 aphorisms which serve as guiding principles for any python hacker . In the python community, a solution or piece of code conforming to these principles is said to be “pythonic”.

  • Beautiful is better than ugly.
  • Explicit is better than implicit.
  • Simple is better than complex.
  • Complex is better than complicated.
  • Flat is better than nested.
  • Sparse is better than dense.
  • Readability counts.
  • Special cases aren’t special enough to break the rules.
  • Although practicality beats purity.
  • Errors should never pass silently.
  • Unless explicitly silenced.
  • In the face of ambiguity, refuse the temptation to guess.
  • There should be one– and preferably only one –obvious way to do it.
  • Although that way may not be obvious at first unless you’re Dutch.
  • Now is better than never.
  • Although never is often better than *right* now.
  • If the implementation is hard to explain, it’s a bad idea.
  • If the implementation is easy to explain, it may be a good idea.
  • Namespaces are one honking great idea — let’s do more of those!

These principles are also distributed with python (ofcourse its “batteries-included” 😉 ), hidden like an easter-egg . Just type the following at the python interpreter prompt to view it.

import this

How to write your own IM program/GTalk client in Java August 7, 2008

Posted by razasayed in programming.
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Here i will show you how you can write your own simple gtalk client using an open source java library called “Smack“. Smack is a cross-platform Open Source XMPP (Jabber) client library for instant messaging and presence , and as you will see it actually makes writing your own client to connect to any jabber service a breeze 🙂 . The library is extremely versatile but to keep things simple, here we develop a program to exchange messages with a buddy of yours in GTalk.

But before we start, what the heck is XMPP and Jabber ? . If you already know this you can skip to the next part.

You see there are many, many IM clients around. Companies such as Microsoft, and Yahoo provide IM services based on proprietary messaging protocols, and also provide popular client software (Microsofts MSN Messenger and Yahoos Yahoo Messenger) using these protocols. Many third-party clients also work with these protocols. However, these protocols remain proprietary and closed, which tends to make them difficult to work with for a developer.

Jabber is an open, XML-based “standard” for instant messaging and is an open source alternative to the proprietary messaging protocols . Jabber uses XMPP (Extensible Messaging and Presence Protocol), which is an “XML based protocol” , for transferring messages. Since the Jabber messages are transmitted in XML form it makes it easy for developers to work with them. Googles instant messaging service uses the Jabber protocol .

OK, now lets get our hands dirty with some code, shall we ? 🙂 . Alright, here we go .

Step 1) To start with download the Smack API

Step 2) Create a folder for your project. Create a lib subfolder . Unzip the downloaded zip file and copy the following files to the lib subfolder : smack.jar, smackx.jar,smackx-debug.jar.If you want you can also copy these files to any other location of your choice and then add the location of these files to the classpath.

Step 3) Now we write the actual code for implementing our gtalk client. To do that first create a file MyGTalkClient.java in your main folder, or anywhere else if you have added the location of the jar files to your classpath.

Step 3.1) The first step is connecting to the GTalk service  The code below does that :


ConnectionConfiguration config = new ConnectionConfiguration("talk.google.com",5222,"gmail.com");
XMPPConnection connection = new XMPPConnection(config);
connection.connect(); /* Connect to the XMPP server  */
connection.login("username","password"); /* Login to the IM service */

“talk.google.com” is the host. 5222 is the port number and “gmail.com” is the service name.

Step 3.2) To send a message to a buddy we use the Chat class as follows :

Chat chat = connection.getChatManager().createChat("friend@gmail.com",new MyGtalkClient());
chat.sendMessage("Hi"); /* Send the message  */

The first argument to createChat method is obviously the email id of your buddy in GTalk . The second argument is an instance of a class that implements the org.jivesoftware.smack.MessageListener interface . This listener interface receives incoming messages and calls its processMessage method to process the message.

Step 3.3) Now, the next step is making sure that we receive the messages that our friend sends . To do that we implement the processMessage method of the MessageListener interface as follows :


public void processMessage(Chat chat,Message message) /*Callback method from MessageListener interface . It is called when a message is received */
{
        System.out.println("Received message: " + message.getBody());
}

Step 3.4) After you are done chatting with your friend you can disconnect from the server as follows :


connection.disconnect() ; //Disconnect 

There we are . A simple bare-bones Jabber client to connect to the GTalk service is ready ! .The final code looks like this .

Step 4) If you have not added the locations of the jar files to the classpath , you can compile and run your chat client as follows :


javac -cp lib\smack.jar;lib\smackx.jar;lib\smackx-debug.jar MyGTalkClient.java

java -cp lib\smack.jar;lib\smackx.jar;lib\smackx-debug.jar;. MyGTalkClient
(Note the ;. at the end of the classpath)

Thats all there is to it ! . From here on you can explore the API, and try to come up with really cool ideas for using instant messaging and presence in your applications.

Happy Hacking !! 🙂

Isn’t RoR scalable ? August 5, 2008

Posted by razasayed in programming.
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A recent piece of news doing the rounds is that Twitter , the microblogging service provider is moving away from Rails framework, due to outage problems,and planning to start from scratch with PHP or Java . However, Evan Williams the co-founder and CPO of Twitter has denied this .

The Missionaries and Cannibals problem and AI July 27, 2008

Posted by razasayed in programming.
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The Missionaries and Cannibals problem is a cute little puzzle, which involves moving 3 missionaries and 3 cannibals from one end of the shore to another  in a boat which can accomodate at most two people at a time . Also, if the cannibals outnumber the missionaries on one side then the missionaries get eaten up by the cannibals.

Well, this sounds like just another one of those river-crossing problems which most people are familiar with since childhood ,  so whats so special about this one ?. Actually, the missionaries and cannibals problem is a famous toy problem in AI (Artificial Intelligence), because it was the first paper that approached problem formulation from an analytical standpoint . Many computer science students might already be familiar with this problem, and also others like the Towers of Hanoi, n-queens problem, the knights tour etc…

I have posted the puzzle below , so that you can have some fun with it  . Its actually a simple problem and i managed to solve it in 11 moves, see if you can do it in less than that  🙂 .  If you do, then hats off to you , because i dont think it can be done in less than 11 moves . Because,with 1 missionary and 1 cannibal 1 move is required,with a pair of each 5 moves, and here in a case of 3 each, i required 11 moves.So it seems that there is a pattern in the minimum number of moves required. 1 = 12+0, 5 = 22+1 , 11=32+2 .

I thought it would be fun trying to develop an algorithm to solve the problem for the general case of n missionaries and n cannibals  , for which i thought the minimum number of moves required would be n2+(n-1). But luckily for me, before i embarked on my search for the solution , i came across some information related to the problem (thanks google ! ), which pointed to the fact that my search would never end ! . The special thing about this problem is that it does not scale up ! . For 4 or more missionaries and cannibals, the problem has no solution ! .

Alright, enough of math !!…let the game begin 😉

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