Category Archives: ruby

Java and Ruby: how language principles influence users’ mindsets

I’ve been doing some Java development lately and Java’s verboseness sent me looking for a way to shorten some of the monstrous generic type declarations. I know there is no typedef or similar concept in Java, but hoped that maybe some Java or Design Patterns gurus invented some clever trick or pattern to do something similar. It’s better to use a ThreeLevelHashMapOfStrings type instead of HashMap<String, HashMap<String, HashMap<String, String>>>, right?

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Using assert’s message to boost your unit testing productivity

Here’s a quick tip for enhancing your test writing productivity: use assert‘s last parameter, the message. Virtually all assert_... methods accept it. You may have noticed in the docs that the last parameter is always message = nil or message = "". Too bad the docs don’t give examples on how to use this message. So, let me fix that.
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TextMate shortcuts you should be using

This is my list of TextMate‘s keyboard shortcuts that are very useful for Ruby and Rails developers, but are not used as widely as they should (according to my very scientific observation on a very representative sample, i.e. my colleagues). I skipped all the obvious ones (like “open file”, “save file”, “go to next window”, “close window” etc.) that most people use anyway. My list includes shortcuts that are very useful but sometimes might be hard to grasp at first or might require a little explanation.
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Cromwell version 0.4 is out!

While you weren’t looking, Cromwell — Lord Protector of your scripts turned 0.4. The new features include:

  • logger support,
  • inspect and change Cromwell’s state,
  • restore original traps after protection end,
  • custom traps support.

…and I have run out of To Do list items. So if you use Cromwell (the gem has been downloaded 165 times from Gemcutter as the time of this writing and the github project has 22 watchers so I assume there are some users of it) and you miss some feature or you found some bug or incompatibility, let me know. Otherwise, happy protecting!

Exploiting obscure Ruby quirks for fun and profit

Here’s one quirk I accidentally discovered in Ruby. Check this out (this is copied from my irb session):

>> defined? x
=> nil
>> x
NameError: undefined local variable or method `x' for main:Object
	from (irb):2
>> if false
>>   x = 3
>> end
=> nil
>> defined? x
=> "local-variable"
>> x
=> nil

What’s going on here?

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Introducing Cromwell — Lord Protector of your scripts

I’m back after a few months hiatus to present you a shiny new gem of Ruby technology: Cromwell — Lord Protector of your scripts. From the README:

[Cromwell] allows you to easily protect your scripts from being killed while they are doing something that should not be interrupted (e.g. interacting with some non-transactional service) or is too costly to restart (e.g. long computations).

More info and examples can be found on Cromwell’s github page. Gem is hosted on Gemcutter, so installation should be as easy as sudo gem install cromwell.

The API and code are minimalistic for now, but I have some features planned for upcoming versions. While signal handling isn’t rocket science, I haven’t yet seen a gem to do it in a more convenient way than Ruby’s Signal.trap. It would also be good if the gem provided compatibility layer over some OS’s quirks if possible.

Comments, suggestions, bug reports and bug fixes welcome. If you find it useful, I’d be glad to hear it. If you think it’s a piece of crap, I’d like to hear that, too :)

And, last but not least, I wish you a Happy New Year 2010!

Eliminating code duplication with metaprogramming

Duplication of code is one of the worst code smells. It should be refactored in order to keep DRY if only possible. This is generally easy. But what if the code itself is not duplicated, but its structure is? That could be a little bit more difficult, but with Ruby‘s metaprogamming facilities it’s not that hard. Read on to see how.

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