Minimalists VS Humanists—A tempest in a teapot is brewing over the proper design of a class API.

Martin Fowler VS Elliotte Rusty Harold on API Design

There’s a hot debate going on about humane API design. Martin Fowler points out that Ruby’s Array API is very rich, providing the user with lots of options when using it. Elliotte Rusty Harold responded with “A 78 method List class is about three times as bad as a 25 method List class, not three times as good.”

And so the debate rages on. Read the links on the bottom of Martin’s page for other opinions on the topic.

I was going to write a long post pointing out that java.util.List is an interface, and we like to keep interfaces short. Ruby’s Array is not an interface (Ruby doesn’t have interfaces as a language construct) but a class, and the forces that keep interfaces small don’t apply so strongly.

But … I decided not to.

Instead I’m going to point out just a small irony. Elliotte writes:

Another example: Fowler likes the first and last methods in Ruby, but list.first() is not significantly simpler than list.get(0). list.last() is perhaps a little simpler than list.get(list.size() – 1) but only because Java stupidly indexes everything from 0 rather than 1. And how often do you actually need to get the first item in the list?

But java.util.LinkedList provides:

   Object getFirst()
            Returns the first element in this list.
   Object getLast()
            Returns the last element in this list.

Interesting.

Why does Elliotte not use getFirst()? ... Because it is not available in the java.util.List interface. Java programmers typically write:

   List myList = new LinkedList();

And then use myList in their code. Since myList is declared to be a list, the getFirst() method never pops up in their completion menus.

As they say: “Out of sight, out of mind.”

Why the Lucky Stiff provides us with yet another Ruby Goodness.

Try Ruby Now

For those of you who have been living under a rock and have missed this link, you need to check this out:

• Try Ruby

(courtesy of Why the Lucky Stiff)

Via Elizabeth Keogh ...

If an Agile Evangelist falls in the forest and there’s no one to hear him, does he still go on, and on, and on about it?

(link)

RubyConf at a Glance

It was very clear by Saturday that I wasn’t going to be able to blog each and every talk like I had in the past. There was just too much going on and I had too much on my plate to do it justice. Plus there were a lot of people doing a talk by talk blog on the conference, so my additional comments seemed superfluous.

So rather than do a blow by blow descriptions, I thought I would just touch on a few highlights.

Matz’s Keynote Address

Matz subtitled his talk “Weird and Crazy Ideas” and he talked about some of the “stretch” ideas he has for Ruby 2.0. If you are following the Ruby 2.0 discussions up to this point, there wasn’t anything that was a big surprise. But he did give some more details on what we should be expecting.

Two big topics of conversation came out of this keynote. One was the syntax for anonymous functions. The second was the syntax for keyword arguments. See the ruby-talk mailing list before the conference for a discussion of anonymous functions. See ruby-talk after the conference for keyword arguments discussions. Both topics are generating a lot of traffic on the ruby-talk mailing list, so check the mailing lists for any details.

Selector namespaces were mentioned by Matz, but without any hint of how they would be implemented. After the keynote, Rich Kilmer brainstormed some ideas and Paul Brannon actually did a (simplifed) pilot implementation in pure Ruby to get a feel for how they might work.

The Long Tail

One of my favorite talks was Nathaniel Talbott’s talk on the long tail of software development. He explored the question of what happens to software development as the time and cost to develope software approaches zero. He compares it to intercontinental railroad (rails ... get it?) which lowered the cost of traveling to the interior of the US to a point that almost anyone could travel.

Metaruby and Ruby2C

The Seattle group is doing some really exciting stuff exploring what it would take to get the standard Ruby library (currently written in C) defined in Ruby. Its a two pronged approach. Part 1 is the Metaruby effort to rewrite the standard classes is a (rather static) subset of Ruby. Part 2 is the Ruby2C translator that can take a subset of Ruby and rewrite it as C code. If this project is successful, moving Ruby to a different platform (i.e. the Java JVM or .NET CLR) much easier. Ryan Davis and Eric Hodel were the presenters for these two talks.

JRuby and YARV

I see these two projects are very important to the future adoption of Ruby in two different groups. YARV addresses the “Ruby is too slow” crowd, while JRuby addresses the “but it doesn’t interact well with Java” crowd. While neither group is critical to future adoption, Ruby acceptance would be enhanced by addressing their concerns.

My Talks

I did two talks this year. One was in the standard track and was on the topic of Domain Specific Languages written in Ruby. It was well received and seems to seeded some new ideas in some people.

The second talk was a workshop (with Chad Fowler) on Sunday afternoon where we delved into the details of programming with continuations. The other workshop was on Rails, so I expected a light turnout at ours. Surprisingly we had a very good crowd. Presenting with Chad was a lot of fun (I really liked the conversational approach we used) and people seemed to enjoy it. Plus I worked in playing a video game into the talk.

Other Stuff

I think the best part of RubyConf is not the formal talks, but the chance to meet and talk to people over meals and between sessions. I will post on some of the topics sparked by these conversations in the weeks to come. Unfortunately, I didn’t get to participate in as many code fests as I had hoped (I was too brain dead for serious coding by the end of the day).

I’m already looking forward to next year!

This article was sparked by a some conversations and discussions at RubyConf 2005.

Test VS Behavior

It seems fashionable these days to say that Test Driven Development is not about testing at all, but rather about (fill in the blank), where the blank can be filled with “design”, “behavior” or “specification”. At RubyConf this year, one of the “informal” discussion sessions around the pool area drew a large crowd of people to discuss this very topic.

The RSpec ruby library (from Steven Baker, Dave Astels and Aslak Hellesoy) is a replacement for Test::Unit. Its main focus is to change the terminology surrounding the whole TDD approach to software development. I think this is key … it is not changing anything fundamental about the processes, it is focused upon the words we use in describing the process. But don’t be fooled into thinking this is a matter of semantics only, for the very words we use to describe something shapes our thought processes about the thing we are describing.

BDD, or Behavior Driven Development, is an attempt to improve TDD (Test Drive Development) by emphasizing the behavior specification nature of traditional TDD. By freeing TDD from its test bound terminology, we avoid some of the preconceptions (e.g. “Tests? Yuck!”) that developers bring to the table when discussing TDD.

So What’s Different

So, what’s the real different between RSpec and Test::Unit? Compare these two code snippets. First the “test” version:

  class TestEmptyMovieList < Test::Unit::TestCase
    def setup
      @list = MovieList.new
    end
    def test_size_is_zero
      assert_equal 0, @list.size
    end
  end

And now the specification version:

  class EmptyMovieList < Spec::Context
    def setup
      @list = MovieList.new
    end
    def should_have_size_of_0
      @list.size.should_equal 0
    end
  end

Note: This is from RSpec version 0.2.0 available as a gem from RubyForge. The RSpec guys are currently thinking about using domain specific language for specification. So expect RSpec to change in the future.

We can see that the structure between the tests and the specifications is very similar. Actually, more than similar, they are virtually identical. We just use Context instead of TestCase, use methods with any name rather than those that start with test_, and use object based assertions rather than specific assert methods.

The result is something that reads rather naturally in ruby-accented English. But the functionally is essentially that of Test::Unit, just in different clothing.

Just Semantics!

I hear you saying “But it’s just semantics!” Of course it is. But leave out the word “just”. When conveying meaning, semantics is everything. And one of the important features of Agile developement is to convey the meaning of the code, in the code itself.

Semantics are important!

Is it worth it?

Ok, semantics are important. But is it worth converting all our unit tests into specifications?

Maybe.

I do find the terminology attractive. But I have a large investment in Test::Unit style tests at the moment. And RSpec is still a bit rough around the edges (for example, the error reporting is not quite as mature as Test::Unit’s). And RSpec is going through some major changes at the moment (I mentioned the specification DSL they are playing with).

What would I like to see? One area of specification that current TDD practices tend to be weak in is the specification of preconditions. Preconditions define under what circumstances it is valid to call a method. For example, it may be invalid to call a square root function with a negative argument. Looking at a list of tests (umm … specs), I can’t be sure if negative inputs are not allowed, or if the spec writer just forgot the cover that case.

I’m not ready to switch over to RSpec yet, but it certainly is moving in interesting directions.

What I didn’t talk about

Those of you who were present at the poolside conversation at RubyConf may wonder why I didn’t mention mock objects, since mock objects were a major part of that debate. I see the Behavior VS Test debate to be completely orthogonal to the Mock VS not-Mock discussion. I’ll pick up the mock object debate in another posting, so don’t worry.

Conference Introduction

David Allen Black welcomed us to the conference and gave us some background on the conference hotel. Evidently the hotel was quite the Hollywood get-away spot for a number of years. A lot of our rooms are named for Hollywood stars (I’m staying in the Joan Crawford room).

Top to Bottom Testing (Francis Hwang)

Some really cool ideas on testing. Francis talked about MockFS and mocking in Lafcadio. He emphasizes the importance of testing and making is easy (so programmers will write them) and fast (so programmers will run them).

The question/answer period brought up the whole mock vs stub nomenclature. There was also a lot of discussion on the use of mock databases.

Francis talked about the ability to redefine the standard File and Dir constants to point to the mock file system versions. During lunch I mentioned the Constant Injection technique I used in my OSCON 2005 dependency injection talk.

open-uri: easy to use and extensible virtual file system (Akira Tanaka)

open-uri replaces the standard open method and will automatically use the HTTP protocol to grab web pages and present them as regular file reads. RubyGems uses open-uri for some of its work.

Tanaka also explored some design principles for building APIs and applied them to the open-uri library. He then briefly talked about how to tie into the open-uri Virtual File System (VFS).

JRuby (Charles Oliver Nutter)

I’m really excited about JRuby on many levels. If nothing else, it lowers the barrier to those exclusive Java oriented development organizations. After a rather long dormant period, JRuby development has really kicked off. Charles walked through some current implementation issues and talked a bit about the future directions.

JRuby’s new “stackless” implementation looks very interesting. I’m wondering if using some of the same techniques in the standard C Ruby implementation would make continuations better/faster.

YARV Progress Report (SASADA Koichi)

Koichi started his presentation with his usual humor using some “insider” Ruby jokes (and some “insider” Japanese humor … RubyMa!)

Most of the presentation dealt with many of the techniques used by YARV to be the fastest Ruby VM possible.

Best quote of the slides:

“Dynamicity is your friend, but my ENEMY”

MetaRuby: Reimplementing Ruby in Ruby (Eric Hodel)

MetaRuby is an interesting implementation of Ruby written entirely in Ruby. Coupling this with the Ruby2C project will (should) give you the ability to write almost the entire Ruby system in ruby and yet get comparable performance to a C based system.

Eric shared some about some of the strange implementation issues they ran into as they implemented the C code as Ruby code.

Supper

Up next after supper … the round table with Matz

Dick Hardt’s OSCON 2005 keynote talked about how to identify yourself online. Here’s an IRC conversation the ensued after I accidently issued a sudo command on a friend’s system, one that is monitored very closely by the sysadmin.

[22:35] <paulv>    matthew immediately declared that we were already cracked. :)
[22:35] <matthew>  yeah, it's all good.  Although, can you prove you're Jim?
[22:35] <jweirich> yes
[22:35] <jweirich> ask me a Ruby question
[22:35] <paulv>    implement the Y-combinator!
[22:35] <matthew>  heh
[22:35] <paulv>    then I'll believe.
[22:36] <jweirich> p proc { |le|
[22:36] <jweirich>   proc { |f| f.call(f) } \
[22:36] <jweirich>   .call ( proc { |f|
[22:36] <jweirich>            le.call (proc { |x| f.call(f).call(x) }) })
[22:36] <jweirich> }.call(proc { |recurse|
[22:36] <jweirich>   proc { |n|
[22:36] <jweirich>     if n == 0 then
[22:36] <jweirich>       1
[22:36] <jweirich>     else
[22:36] <jweirich>       n * recurse.call (n-1)
[22:36] <jweirich>     end
[22:36] <jweirich>   }
[22:36] <jweirich> }).call(5)  
[22:37] <matthew>  wow.  This is better than gpg keys.
[22:37] <matthew>  I hope you had that laying around 
[22:37] <jweirich> nah, did it from memory ;)
[22:37] <paulv>    this *is* better than GPG keys.

(and for those that missed the winking smiley, no, I did not do this from memory)

Update

I see that Dick Hardt’s OSCON 2005 presentation on Identity 2.0 is available at http://www.identity20.com/media/OSCON2005. This is worth seeing.

I don’t usually talk must about one-liners, but here’s one I used today.

ARGF and inject ... Two Great Tastes that Taste Great Together

Consider the following ruby one-lineer

ruby -e 'p ARGF.inject(0) { |sum, line| line.split[1].to_i + sum }'

Breaking it down, it …

• Iterates over each line of standard input (ARGF.inject(0))
• Splits the line into colums (line.split)
• Selects the second column ([1])
• Converts the second column to an integer (.to_i)
• Adds to to the running subtotal (+ sum)
• And prints the final sum (p)

In short, it sums up the numbers in the second column of a text file.

Cool. Now combine it with another one-liner …

lynx -dump http://gems.rubyforge.org/stats.html \
  | ruby -e 'p ARGF.inject(0) { |s,t| t.split[1].to_i + s }'

And you get the result …

1005821

... which is the number of gems served by RubyForge to date.

Over 1 million gems served :)

Here’s a story of one of those perfect presentation moments ... inspite of the horror of a demo failing minutes before the presentation starts.

David describes a recent presentation at the Salt Lake City No Fluff, Just Stuff symposium where a live rails demo leaves the crowd speechless.

Ruby Everywhere! Scott Baron has a cool idea that puts Ruby in yet other piece of the web framework.

CSS Builder

Scott was thinking about the problem of redundancy in a CSS style sheet (e.g. repeating the colors of a color scheme a zillion times throughout the file).

His solution? A builder-like CSS constructor. Yes! Ruby everywhere! Go read his blog for the details.