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Test Driven Development in Python

2009-09-28T17:39:00.002+08:00

Here are the slides for my talk at Pycon India this weekend. The talk was on doing test driven development in Python and it looked at 3 frameworks - unittest, py.test and nose.

Test Driven Development With Python

View more documents from Siddhi.

Pattern Matching With PEAK-Rules

2009-05-13T20:59:00.004+08:00

I came across this interesting article on Pattern matching in Python. The article asks: Can we recreate in Python the pattern matching semantics present in languages like Haskell and Erlang.

For those not familiar with the way pattern matching works, I've copied the example from the article above.

%% handle(Path, Method)
handle("/", _) ->
  not_a_resource;
handle(Path, 'PUT') ->
  create_new_resource(Path);
handle(Path, 'POST') ->
  update_resource(Path);
handle(Path, 'GET') ->
  retrieve_resource(Path);
handle(_, _) ->
  invalid_request.

What the above code does is to return "not a resource" if you call the handle function with the path parameter as "/" and any method. If you call handle with any path and method parameter as "GET" then it calls retrieve_resource(Path) and so on.

PEAK-Rules

A method to replicate this in Python was given using match objects, but I thought hey why go through all this trouble when PEAK-Rules does most of this for us?

Multimethod Dispatch

PEAK-Rules is a library that enables multimethod dispatch in Python. Those with an OO background will recognise a specific instance of this in method overloading. When an overloaded method is called, execution can go to different method implementations depending upon the type of the parameters passed. In generic multimethod dispatch, you can route execution based on any criteria that you define. PEAK-Rules brings this sort of generic multimethod dispatch to Python.

An Example

So lets take a concrete example. Our goal is to rewrite the above Erlang code in Python using two libraries: PEAK-Rules and an add-on called prioritized_methods that allows prioritised method ordering.

First, you'll need to get install PEAK-Rules and prioritized_methods. You can pick them up from the links given or if you've got setuptools, then you can just easy_install them.

Then type out the following code:

>>> from peak.rules import abstract, when
>>> from prioritized_methods import prioritized_when
>>> @abstract()
... def handle(path, method):
...     pass
...
>>> @prioritized_when(handle, "path == '/'", prio=1)
... def not_a_resource(path, method):
...     print "not a resource"
...
>>> @when(handle, "method == 'GET'")
... def get_resource(path, method):
...     print "getting", path
...
>>> @when(handle, "method == 'PUT'")
... def create_resource(path, method):
...     print "creating", path
...
>>> @when(handle, "method == 'POST'")
... def update_resource(path, method):
...     print "updating", path
...

Here is what is happening:

We first define an abstract function handle(path, method). Do this by placing the @abstract() decorator on it.

Now consider this snippet:

>>> @when(handle, "method == 'GET'")
... def get_resource(path, method):
...     print "getting", path
...

This defines one implementation for the handle function. It says, when the handle function is called, and the condition given is True (in this case method == "GET"), then call the implementation given below (here: the get_resource function).

Similarly we define the other implementations to be called on some other conditions.

The only thing left is the usage of @prioritized_when. Now, when a call is made to handle("/", "GET"), we see that the condition for not_a_resource as well as get_resource are satisfied. Which implementation should be called? In this case, we use the @prioritized_when decorator and set the priority to 1. This tells the system to give priority to this implementation in case of conflict in match.

Here is how the output looks:

>>> handle("/", "GET")
not a resource
>>> handle("/", "POST")
not a resource
>>> handle("/home", "PUT")
creating /home
>>> handle("/home", "POST")
updating /home
>>> handle("/home", "GET")
getting /home

Pretty cool! The best part of this is that you can dispatch on virtually any condition. While the resulting code is a little more verbose than the Erlang example, its not too bad and it does the job well.

Wall Street Arithmetic

2009-04-02T19:57:00.001+08:00

From Philip Greenspun:

I attended a seminar this evening presented by one of our largest banks (name not mentioned to protect some friendships). A middle manager introduced Eugene White, an economist from Rutgers. “I earned nothing last year,” said the hard-working bank employee. “Zero for 2008. No bonus. No options. No stock.”

Over dessert and coffee I asked one of the guy’s subordinates if the boss wouldn’t also have gotten some sort of base salary. “Sure,” he replied, “but maybe as low as $500,000 per year.” How did that round to zero? “Well, he might have made $12 million the year before.”

And you thought Peano arithmetic was challenging….

10 Trends in ICT: My Talk At VIT Entrepreneurship Awareness Camp

2009-03-15T11:55:00.003+08:00

Here are the slides from my talk at VIT yesterday. The slides may not make much sense without the actual talk though.

10 Trends in ICT

View more presentations from Siddhi.

"Cutting Costs With Agile Software Development" Seminar In Chennai

2009-03-05T17:42:00.003+08:00

The Ministry of Micro, Small and Medium Enterprises (Govt. of India)
(MSME) is organising a 1 day seminar series on "Cutting Costs with Agile
Software Development" on Friday, 20th of March.

Topics that will be covered:

Business Case for Agile Software Development

Introduction to Scrum

Adapting to changing requirements

Benefits of self organising teams

Releasing quality software

Agile metrics

Plus an open discussion where you can bring up the topics you're most
interested in.

Click the image on the left for all the details regarding content and registration.

The crisis of credit explained

2009-03-01T02:31:00.001+08:00

Via hatke, check out this awesome video on the credit crisis:

The Crisis of Credit Visualized from Jonathan Jarvis on Vimeo.

Yahoo Groups running on Python?

2009-01-22T22:07:00.000+08:00

I tried to post a message today and go this error:

My Talk at Genesis

2009-01-18T14:59:00.004+08:00

I gave a talk last Sunday at Genesis in IIT, Madras. My talk was on planning the operations. Here are the slides for the talk. Since they don't make much sense without the commentary, I have attached a bit of commentary as well.

IIT Business Plan Workshop

View SlideShare presentation or Upload your own. (tags: genesis event)

Why Plan

"Would you tell me, please, which way I ought to go from here?"

"That depends a good deal on where you want to get to," said the Cat.

- Alice in wonderland

The first part of the talk was about why you need to plan in the first place. Many students believe that the idea of the operations plan is so that you can show it to venture capitalists and get funded (or perhaps win business plan competitions). The point I tried to emphasise is that the plan is something that helps the entrepreneur with the big picture. Running a startup is not a matter of following a fixed set of steps until you get rich. Rather, you will be fighting fires every day as something or the other goes wrong. When you get consumed with all these small fires, it is easy to lose the big picture, and thats when you need your operations plan to get back on track.

Rules for operations planning
With that I talked about 5 rules of operations planning. Here they are:

1. Know Where You Are
At any point you need to know where you are. If your plan calls for one year of development before you release a product, then you should be able to know if you are on track at any point. For this, you need to have intermediate milestones where you can check your progress and adjust your plan accordingly. For a software startup, I would say you need a milestone at least once a month. This would be a release with a subset of features of the final product.

2.Churn, baby, churn
You may have done a lot of market research, but you cannot gauge the market reaction until you actually get your product or service into the market. Therefore, get it out as soon as possible - even if it is only a small subset of your final vision - and then use market feedback to drive the product. In order to do this, you need to break up your product or service into chunks that are complete and can be released.

3. Be Flexible
Often opportunities arise that could not have been predicted at the start. Maybe users are using your product in ways you did not plan, or perhaps a new opportunity presents itself. A startup needs to be able to take advantage of these opportunities. A small team of generalists will usually trump over a team of specialists, because generalists can change direction quicker.

A story: Sabeer Bhatia and Jack Smith wanted to start a company to do web based databases. It was entirely an accident which led them to develop the first web based email system - Hotmail.

4. Know What Is Important
You need to know what is important for the product to be developed. Focus on what needs to be done to get your product in the hands of your target customers. Startups will sometimes spend money on a nice office and save money on developer workstations. While this is great for the founder's ego, it's counterproductive for the business. As far as operations go, spend on productivity enhancements rather than ego enhancements.

5. Be Ready To Start Again

"Plans are useless, but planning is invaluable" - Dwight Eisenhower

Operations planning is not something that you do at the start, but it's something you need to be continuously doing. New information keeps coming up which invalidate your old plans. Rather than stick to the old plan, throw it away and plan again. Don't be attached to your operations plan - its essentially useless - but the act of planning is very useful.

Silver Catalyst reviewed by BangaloreInc

2009-01-06T11:45:00.003+08:00

Silver Catalyst has been reviewed by Praveen over at Bangaloreinc. Check it out: Silver Catalyst - Web Based Agile Scrum Tool For Agile Bookkeeping.

Silver Catalyst: Agile Project Management

2009-01-03T15:09:00.002+08:00

We've been pretty busy at work at Silver Stripe Software and today we're happy to announce the release of the online version of Silver Catalyst.

Silver Catalyst is a project management tool for teams that follow an agile software development model. We're in beta and there are a few free accounts during the beta, so if you are doing agile development, you might be interested in giving Silver Catalyst a run. Head over to the Silver Catalyst website and sign up.

Proto.in Registrations Open

2008-12-25T10:33:00.001+08:00

Registrations for the fifth edition of Proto.in are open! You can register here - http://proto.in/register/

Proto.in is an event that aims to bring together startups, investors and industry people in one location. Its a two day event. The first day will have a number of talks on startups. Usually these cover topics like funding, business plans, bootstrapping and so on. There are also technology talks. The second day has some selected startups presenting their product followed by an open house where you can interact with startups and investors.

This event is the fifth edition of Proto.in. The first three editions were in Chennai, the fourth in Delhi. This edition is going to be held in Bangalore, so its pretty convenient for people from Chennai to attend.

Find out more about Proto.in here - http://proto.in/

The cost of registrations is Rs.750 for one person or Rs.1000 for two.

Again, this is the URL - http://proto.in/register/

Zebras fight for dominance

2008-11-08T10:55:00.001+08:00

Zebras fight for dominance
Originally uploaded by Siddhi

I took the photo on the right in September. It shows two zebras fighting for dominance.

This is part of a complex ritual that zebras use to show dominant behaviour. It starts with zebras pressing sides together and rubbing cheeks and ends up with both zebras jumping on their forelegs. The entire ritual is explained in more detail on this page.

The first time I saw this, I was completely unprepared to take a photo. I have a photo with the heads cut off because I didn't expect them to stand up. I was better prepared after reading about the ritual. The next time I saw a zebra issue a challenge, I waited with the camera in position knowing that they will eventually jump. The result is this photograph.

Chennai OCC November Meet: New venue - Ascendas Food Court

2008-11-01T23:22:00.004+08:00

The November meetup of the Chennai OpenCoffee Club is tomorrow. There is a change in venue this month. We are meeting at the Ascendas food court at 3pm instead of the usual location at Amethyst. If you have never been to this food court, then the website has a handy map with the location of the venue. Basically it at Taramani, behind IIT and Tidel Park.

Now if you are unsure of what the Chennai OpenCoffee Club actually is, its a place for entrepreneurs, would-be entrepreneurs, and everyone else involved with startups to meet informally (that means no need to join a group or pre-register and no entry fees). We have a meet on the first Sunday of the month. The meetups are open to everyone. Join the Chennai OCC website to get an email notification before every meetup.

On the topic of the OCC website, I just wanted to point out the Chennai OCC website has a forum, so do join in the coversations.

Plus a new feature that is available is that all discussions on the website are now available as an RSS feed — Click here for the Chennai OCC forum feed — so its a really good idea to subscribe to the feed in your favourite blog reader. That will allow you to keep track of the Chennai OCC forums and, if you have joined the website, you can then join in the coversation.

Must watch videos from DjangoCon

2008-10-22T10:44:00.003+08:00

I was recently going through some of the videos from DjangoCon. Two must watch videos are Cal Henderson's talk titled "Why I Hate Django" and Mark Ramm's talk "A Turbogears guy on what Django should learn from Zope". Both Cal and Mark bring in interesting outside perspectives that I hadn't really considered before. Both talks run around an hour each and are well worth watching if you have the time.

Cave Story coming to WiiWare

2008-10-09T00:04:00.003+08:00

The most exciting news I've heard in a while. Cave Story is coming to the Wii through its online WiiWare distribution channel. Cave Story is a totally kickass game. It's actually a free game on the PC (Get it here). I played it earlier this year and it was really awesome (Cave Story Review). And it's free. So I can hear you ask - if I've already played it, and its free on the PC, why pay to play the same game again? Hmm, good question. Because its an awesome game? Plus a good way to give back and support the time put into the free game. And there is going to be new content not found in the free game. Can't wait for this one.

Choosing a scripting language

2008-08-31T18:11:00.004+08:00

CIO magazine has an article titled You Used THAT Programming Language to Write WHAT? They took five "scripting" languages — Ruby, Python, Javascript, PHP and Perl — and then get Zed Shaw, Martin Aspeli, Michael Morrison, Kenneth Hess and James Turner to write about what kind of applications the language is good for, and where you are better using another language. Check it out.

Formation

2008-08-22T20:20:00.001+08:00

Formation
Originally uploaded by Siddhi

F-16s fly overhead. Singapore National Day, August 2003

Github and Webfaction rock

2008-08-15T11:08:00.001+08:00

Just wanted to chip in and say that Github rocks. And also Webfaction.

India Unconferences and Events

2008-08-14T11:24:00.000+08:00

Chennai OCC isn't the only thing to turn one year old this month. India Unconferences and Events, a group to track unconferences and community events in India also turns one.

Over the last year, the number of community events has increased by leaps and bounds. There is an event happening somewhere almost every week. Unfortunately, it isn't always easy to track these events. Often, you only find out about the event when someone blogs about it after it's over :(

Thats where the India Unconferences and Events group helps. This group tracks tech and startup community events happening around the country. Over the last year, this group has tracked more than 120 events around the country (check out current events and past events tracked by the group)

Once you join this group (you just need a Yahoo ID to sign up), you can subscribe to the RSS feed to be notified of events as they are added. It's an open group, so if you come across a tech community event that is not in the group, you can add it to the group.

The problem with ebooks

2008-08-05T11:03:00.003+08:00

The problem with ebooks is that its too easy to lose them. I recently bought an ebook, and now I have no idea in which directly I put it and I can't find it. Rather more difficult to lose a paper book. How do you solve this problem? Do you keep burning ebooks to a CD after you buy them? Give me some ideas.

From Good To Great ... To Below Average

2008-07-31T15:49:00.004+08:00

There is an interesting post on the Freakonomics blog titled From Good to Great … to Below Average. The post talks about how many of the companies profiled in the book are not all that spectacular today.

Ironically, I began reading the book on the very same day that one of the eleven “good to great” companies, Fannie Mae, made the headlines of the business pages. It looks like Fannie Mae is going to need to be bailed out by the federal government. If you had bought Fannie Mae stock around the time Good to Great was published, you would have lost over 80 percent of your initial investment.

And at the end:

What does this all mean? In one sense, not much.

These business books are mostly backward-looking: what have companies done that has made them successful? The future is always hard to predict, and understanding the past is valuable; on the other hand, the implicit message of these business books is that the principles that these companies use not only have made them good in the past, but position them for continued success.

Read the whole post here.

Designing Sustainable Startups

2008-07-30T18:12:00.002+08:00

via Sampad: Niraj Bhatnagar's presentation at Barcamp Delhi 4.

Designing Sustainable Startups

view presentation (tags: entrepreneurship sustainable business social)

Funny gmail bug

2008-07-27T15:16:00.002+08:00

Spotted this in my Inbox today. Although it says -64 mails, all the mails are there, so I suppose its kind of a harmless bug.

Window with Sunflowers and Pine Cones

2008-07-24T11:54:00.001+08:00

Window with Sunflowers and Pine Cones
Originally uploaded by Siddhi

Window in Roussillon a small ochre mining town. Near the town are some beautiful coloured cliffs.

Chennai OpenCoffee Club Turns One!

2008-07-19T11:48:00.012+08:00

It's hard to believe but the Chennai OpenCoffee Club will soon turn 1 year old. Vaidhy and I started it with the first meetup on the 5th of August, 2007 at Subway (Read about it here). Since then, OCC has spread out to Bangalore, Mumbai, Pune, Hyderabad, Delhi, Noida and Kolkata (See the links at the bottom of this post to join these OCC groups).

What is the Chennai OpenCoffee Club?

Here's the blurb from the website

The Chennai OpenCoffee Club is a place for people involved in the startup ecosystem to meet in an informal setting. Anyone involved with startups - entrepreneurs, developers, lawyers, investors - is invited to come and join the conversation.

Chennai OpenCoffee Club Links

Media Coverage

OpenCoffee Clubs In Other Cities

If you are from another city or traveling, you might want to catch up with one of these other OpenCoffee Clubs