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Posts Tagged ‘Programming’

Introducing gabriel


If you’re running a large-scale Ruby project, chances are that god is monitoring your long-running, background processes. I’ve had some encounters with god and I decided that I was fed up with not having tab completion for it.

So I created gabriel. gabriel helps you communicate with god by offering completions for subcommands, options, tasks, and group names for your bash shell. Installing it is pretty simple:

$ gem install gabriel
$ gabriel-install
(From there, follow the on-screen instructions)

To ensure you get completions in every session, confirm that your .bashrc is sourced in your .bash_profile (or .profile, if you’re a bit more old-school).

This is my first foray into shell scripting and into publishing a ruby gem, so check out the source and if you can make gabriel even better, please do contribute your patches.

May god watch kindly over all of your processes.

Context Switching

(Miscellaneous, Programming)

One of the reasons this blog is called “Live & Code” is because Computer Science (and by extension programming) is one of the lenses through which I view the world. There are often parallels between the way we think and the way computers work. I don’t think that this is an accident; the term “computer” used to refer to a human being whose profession was computing values. These people would sit and work through algorithms to calculate values that would be used in scientific research.

One of these parallels between humans and computers is the way that we multitask. Computers only seem to multitask by switching between tasks rapidly, with the exception of new multi-core and multi-processor systems, which can run as many tasks in parallel as there are cores or processors. So it was interesting to read recently that the prevailing theory is that humans multitask in precisely the same way!

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Life advice in code

(Personal Development, Programming)

Live & Code has been largely about programming and life lessons. So, you can imagine that I was incredibly delighted to see these two combined in a small exchange on Facebook started by Reginald “raganwald” Braithwaite.

Life Advice in Code (raganwald)

Self-esteem expressed in Ruby

It’s a valuable life lesson made incredibly concise in my favourite programming language, Ruby. I leave the interpretation to the reader. It relates to some themes that I’ve already written about before and will probably write more about in the future.

LDAP-based RBAC with ActiveLdap and declarative_authorization


If you followed my previous tutorial on implementing pass-through authentication to LDAP with Authlogic, you might be wondering how it can be extended to give different permissions to members of different LDAP groups. ActiveLdap and declarative_authorization make this incredibly simple.
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Adventures in Ruby: When Constants Aren’t


I just squashed a bug that had me scratching my head for at least a good half-hour or so involving a class constant that kept on getting changed. Here’s the setup (anonymized so that I’m not exposing gooey proprietary secrets):

class WebTransaction
  # Base URL for transaction web service
  def transaction_url
    url = SERVICE_URL
    url << "VAL1=foo"
    url << "&VAL2=bar"

The class is meant to represent a transaction being posted against a rather odd web service that actually uses GET rather than POST for posting transactions (bad web service!). In my actual code, the URL parameters appended to the SERVICE_URL base would be determined on a per-object basis but I’ve simplified it here.

Here’s the punchline: SERVICE_URL was changing! Calls to transaction_url would keep on appending more variables to it. If you’re particularly clever with Ruby, you’ve already figured out exactly why. But if you’re scratching your head like I was, here are some hints:

  • In Ruby, constants aren’t. In fact, they’re really no different from variables except for the fact that Ruby detects that variable names in all-caps are probably supposed to stay constant and warns if you try to assign to them.
  • <<, for strings, will append to the end of the string.
  • Ruby strings are mutable. That is, operations on a string variable will usually be done in place, rather than returning a new string. (Method calls, on the other hand, are a different story!)
  • Assigning a String variable to another String variable will assign the reference. That is, the two variables will be pointing at the same object.

Hit the jump to see the solution to this little mystery…
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“So… what do you do?”

(Personal Development, Programming)

I think that this is a dreaded question for many programmers and others in fields with a scientific or mathematical bent. How do you explain the full extent of what it is that you do and why it’s valuable without being dismissed as just another creepy nerd? How do you fight the stereotype of unkempt basement-dwellers living with their parents, spending most of their time on the Internet because they’re too socially awkward to interact with people in other settings?

About a week ago there was a discussion about this on programming Reddit. The original poster, a programmer, feels a sense of inferiority because while others can succinctly explain the “awesome” in what they’re doing, he cannot. I sympathize with this sentiment. I love what I do but how do I transfer that passion without drowning the other person in the technical details? It feels like without the finer, technical details, my job description becomes distilled to “I make websites.”

Really? That’s it? That’s what I do for a living?

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LDAP Pass-through Authentication with Authlogic and ActiveLdap


Today, I pushed a branch to my fork of authlogic_example: with-activeldap.

This branch shows a way of implementing pass-through authentication to an LDAP server using ActiveLdap and Authlogic, with just some small changes to the User and UserSession models.

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Where is why?


“Why The Lucky Stiff”, one of the most influential characters in the Ruby community, has simply vanished. His Twitter account, GitHub account, and most of his websites are gone without a trace.

Why The Lucky Stiff’s contributions to the Ruby community include “Why’s Poignant Guide to Ruby”, a book which many state was the reason they got into Ruby, Shoes, an easy-to-use cross-platform GUI toolkit with innovative online distribution features, and Hpricot, a very slick HTML parser that is also a joy to use.

Some believe that he has decided to move on from software development because his last tweet reads “programming is rather thankless. u see your works become replaced by superior ones in a year. unable to run at all in a few more.” Some believe that his accounts were all hacked. A few others believe that his anonymity has been compromised and that he has decided the destroy the pseudonym.

Wherever Why The Lucky Stiff goes from here, I hope he knows that there are so many of us who looked up to him and have him to thank for knowing the joy that is programming in Ruby. He will be sorely missed.

The True Spirit of Open Source


Very rarely does something completely disconnected from my day-to-day existence annoy me so much that I feel the need to say something, but this is something I feel very strongly about.

Robert Fischer wrote a post titled “Dear User of My Open Source Project” and many of the proggit comments were quite vicious. I noticed that some of these commentators seemed to have the same understanding of “open source”: that an open source project is a product, like any other product, that is simply distributed with its source code. Therefore, Robert is clearly creating and releasing “inferior” products and this behaviour should be punished. Being open source is not an excuse.

If this is your understanding of open source, you have missed the point. Entirely.

Yes, there are open source projects out there that are very well-documented, quite reliable, and have attracted large communities of contributors that tirelessly work to improve every aspect of the software. But by my count, that seems to be the exception rather than the rule. Most open source projects out there are maintained by just one person who scratched an itch and thought the solution might be useful to others. Some of these projects might be lucky enough to have a few passionate contributors. These projects may have some rough edges in their code or their documentation, and perhaps the contributors might be too busy to put on the appropriate polish.

You might think that irresponsible, or even reprehensible. How dare this person release this garbage and pollute the open source community!

News flash: it is these people who drive open source software. Those large, reliable open source projects with all of the sparkle and polish? They became that way because large groups of people found them useful enough that they decided to invest their time in making the project even better. But in all cases, for open source software to progress, people have to be willing to give up their time and energy for free and with no expectation of reward. Open source is driven by pure altruism.

And yes, as a programmer using open source software, you may sometimes have to roll up your sleeves, get into the code, and make the changes that you need. Or perhaps you can find other ways to contribute. But complaining like a petulant child that it doesn’t serve your particular purpose is, frankly, incredibly rude considering that you were given this software entirely for free and given the power to inspect its source code and change it to suit your needs. If that is the way that you’re going to approach these projects, go use something else.

Like Christmas, the true spirit of open source is giving.

Edit: Some one on proggit rightly pointed out that I’ve made a common mistake of grouping “open source” software with “free” software, a subtle distinction that this pagefrom the FSF makes very clear. However, I believe that Robert Fischer’s post and his complaints also referred more to “free” software than “open source” software. Consider, for example, that he prefers to use the WTFPL for his projects, the spirit of which is “I’ve decided to put this out here, and you guys can do whatever you’d like with it.”

This is not to say that all “open source” software doesn’t adhere to the values of “free” software or that all “open source” software necessarily follows the values of “free” software.

A Rails Puzzler


While I refuse to call this “magic”, the following has been confusing me for a long time now and I’ve finally decided to post it to my blog and see if anyone else gets it.

It turns out that ActiveScaffold and YARD don’t play nice together. In particular, if YARD has previously been loaded (say, to define a Rake task for it), ActiveScaffold initialization will fail with the following error:

uninitialized constant Helpers::ControllerHelpers

Using --trace and following the source code, I find out that this is happening during ActiveScaffold’s initialization, particularly at this statement:

ActionController::Base.send(:include, ActiveScaffold::Helpers::ControllerHelpers)

Debugging the ActiveScaffold initialization code yields this baffling result:

>> ActiveScaffold::Helpers
=> Helpers
>> ActiveScaffold::Helpers::ControllerHelpers
NameError: uninitialized constant ActiveScaffold::Helpers

It’s the weirdest thing that I’ve seen since I became a Rubyist and it is blocking me from using YARD to generate the documentation for my current Rails project. Unfortunately, cutting out ActiveScaffold isn’t going to fly because the deadline for initial release is so close and so much functionality is implemented using it already. It wasn’t my choice; if I had my way, I might never use ActiveScaffold ever again.