9th - 15th May 2005

Ruby Weekly News is (usually) a summary of the week’s activity on the ruby-talk mailing list / the comp.lang.ruby newsgroup, brought to you by Tim Sutherland.

This week it’s a catchup double-dose – the last two weeks rolled into one.

Articles and Announcements

User Group News

  • Hamburg.rb meeting

    • Stephan Kämper said that the Hamburb.rb group were having a meeting on May 4th.

  • Any Rubyists in Oslo?

    • Chris Pine is moving to Oslo this year and was “wondering if there are any fans of Ruby up there?”

    Kent Dahl said that indeed there were, and suggested looking at NorwayRUG.

  • unless baltimore.rb?

    • Sam Goldman said “If anyone wants to set up a ruby meet-up in Baltimore I can get us a very nice conference room at my university and probably free pizza.”

  • List Invite - London Ruby Users Group

    • Robert McGovern announced a new list for the London Ruby Users Group.

  • Yahoo group for Austin (and) Texas Ruby users

    • Hal Fulton announced that the first meeting for the Austin and Texas group had been held. “Mexican food was consumed and plans for code were laid.”

    The group will probably use the name “ARCTAN” – “Austin Ruby Coders’ Texas Area Network”.

  • phoenix.rb

    • James Britt announced the next meeting of the Phoenix Ruby Users Group (on the 12th of May).

    “b.square unless b.there?”

  • Central Ohio Ruby Users

    • Joe OBrien introduced a new group – the Columbus Ruby Users Group (Central Ohio in the U.S.).

    “Please, come one come all.”

Quote of the Week

    John Carter in What sound does no duck make?,

    Imagine a flock of ducks in the sky. Listen. Now remove the ducks. Listen.

    What is the sound of no duck quacking?

    What should nil respond_to?

    Ryan Leavengood gave the best response.

    (If you’re confused, see the “RCR 303…” thread below.)

Threads

ruby-dev summary 26011-26089

SASADA Koichi posted the latest English summary of the Japanese list ruby-dev.

The CVS version of irb now has improved “save history” support, and mkmf supports C++.

String Hashing Algorithms

String hashing algorithms were discussed. Phrogz benchmarked some algorithms, and Zed A. Shaw gave alternatives to hashing.

RCR 303: nil should accept missing methods and return nil

John Carter suggested changing nil to never raise NoMethodError. Instead, when a method of nil was called which otherwise did not exist, nil would be returned.

“Not only does this simplify ruby programs considerably, it also changes certain crash bugs silently into correct programs.”

Matz replied with:

I know Objective-C’s nil works like that. I once developed an OOP system (which was an early version of Ruby) where nil would respond to all undefined messages by doing nothing. In production code, it does nothing bad, since any production code should not raise an exception. Rather it introduces new scheme of error handling.

But during development, it can hide bugs. It is very difficult to distinguish correct error handling by ignoring unknown message, and uncontrolled unintentional misbehavior caused by bugs. It’s against the principle of “early death”.

Regarding John’s assertion that the proposed behaviour wouldn’t hide bugs in real code, Austin Ziegler said that “I can tell you from experience over the last four days that I have fixed no fewer than five *real* bugs in PDF::Writer that would have resulted in the incorrect generation of PDF output had I done this.”

A number of others also thought the proposal was a bad idea.

John started a new thread No Thing Here vs Uninitialized and RCR 303 (under the nickname “Cyent”), which argued that nil is “overloaded too heavily” - we should distinguish between ‘uninitialised’ and ‘nothing’.

Christoph said this sounded like Javascript (ECMAScript), which has both null and undefined.

Rubyist formerlly known as Newbie

Jason Ashbaugh posted a “Thank you” to Chris Pine for his Learn to Program tutorial that teaches programming using Ruby.

“I started learning Ruby about 2 years ago (something came up early on, and I had to drop most of my “learning” activities). Chris’ introduction to programmning was much shorter then :). But About two months ago I decided I had time to finally learn to program, and I knew Ruby was still the language I wanted to learn, so I google for “Ruby Pine” (I still remembered his last name it made such an impression) and I printed out your webpages.

After two months of toting them back and forth to work on a clipboard I finally feel like I understand enough programming to start learning :)”

ruby-dev summary 26090-26127

A symlink security problem was found with FileUtils.rm_rf.

Ruby on Windows CE?

Volker Voigt asked if Ruby could run under Windows CE.

nobu replied – “Yes, see wince/README.wince” in the source for information.

AIX Status?

Jaime Fournier asked what the status of Ruby support on AIX was. There had recently been discussions of problems with the socket library on AIX.

KUBO Takehiro said that the CVS version now works on AIX 4.3.3.

Redesign 2005, Round Two

With a paraffin banjo on his knee, why the lucky stiff presented Round Two from the ruby-lang.org website redesign team.

There were many favourable comments on the design, plus discussion on the logo and slogan used. A sexless duck stole the fish’s bicycle.

How to interface with an API written in C++?

Derek Haskin asked how he could call C++ functions from Ruby.

Nikolai Weibull posted a couple of links, the first of which was a link to the excellent ruby embedded into c++ article by Simon Strandgaard.

It demonstrates how to use C++ classes from Ruby, and vice versa, both with and without SWIG.

Piers Harding said that you could always use extern "C" around the C++ code to provide a C interface which Ruby would then use.

Gennady Bystritksy recently started using SWIG and was very impressed.

“It transforms your C++ classes into Ruby classes practically seamlessly, even giving you opportunity to adjust to naming conventions simply by edditing a SWIG interface file. Included typemaps allow you, for example, return std::string from your C++ method, aautomatically gets converted and returned to the Ruby world as Ruby string, without you doing a stir. Isn’t it amazing? ;-)”

Ruby/DL SendInput

Peter C. Verhage wanted call SendInput, a win32 function from the user32.dll Windows library. (Roughly, he wants to use Ruby to call a particular C function.)

“Unfortunately this method takes some complex arguments; several nested structs, including a union and a pointer to an array of a certain struct etc. How can I use Ruby/DL to call this method?”

Takaaki Tateishi gave a link to sendinput.rb from his “DL Cookbook”, which shows exactly how to do this. It uses DL2, the ‘next generation’ version of DL.

One interesting line in the code was 
extern "UINT SendInput(UINT, LPINPUT, int)", :stdcall

Note the second argument to extern, which indicates the calling convention that should be used. This matters on Windows platforms, where different functions often have different calling conventions, and is a new feature of DL2 over the original DL.

Rendering text with OpenGL

Ilmari Heikkinen wanted to render nice-looking text onto an OpenGL texture. “By nice-looking I mean variable width anti-aliased truetype fonts with different font sizes, hinting, line heights and all the usual font rendering lib niceties.”

George Ogata said that GLUT has simple text-rendering, or you can use libfreetype to render to a 2D image buffer. (Both GLUT and libfreetype have Ruby bindings.)

Alternatively, there was the FTGL library. “It has lazy-loaded, texture-based fonts for fast rendering, and extruded geometry fonts for when you want render text as a solid object from different angles.” Unfortunately, it doesn’t (yet) have Ruby bindings.

Bill Kelly thought that FTGL sounded great, and plans to write bindings for it in the next month or two.

Ilmari himself went for rcairo, a Ruby interface to the Cairo vector graphics library.

another Tk question

Joe Van Dyk asked, “In Tk, what’s the best way to show a large table of data that gets constantly updated?”

Hidetoshi NAGAI said that the TkTable extension can be used for this. Ruby/Tk support for it is included with Ruby.

Relax NG validator in Ruby?

Miles Keaton asked if there was a Relax NG validator for Ruby. The only library he could find was for Java.

(“Relax NG” is an XML schema language, defining elements such as list and define.)

James Britt said that REXML has some experimental support for this.

Amazing Mazes (#31)

Matt Linnell wrote Ruby Quiz number 31.

“We’ve had crosswords, cryptograms, chess puzzles, madlibs … so why don’t we try our hand at mazes?”

There were two parts; writing a program to generate a maze, and writing one to solve it.

ruby vs. java?

Franz Hartmann, a physics student from Berlin, asked about using Ruby to do physical model calculations.

The appropriateness of Ruby or other languages for this task was debated. Michael Ulm suggested GNU Octave, a language designed for numerical computations.

Fortran, Mathematica and others were also mentioned.

“maybe its the inbreeding but i am confused” was uttered.

Object#inside_metaclass?

This was another thread considering the issue of what to name the obj in

class FrederickTheFrog
end

fred = FrederickTheFrog.new
obj = class << fred; self; end
obj is a class that belongs only to fred. You can define methods in it that are only for fred – no other instances of FrederickTheFrog will have them. (This is the exact reason such a concept exists.)

The usual syntax for adding such a method is as follows,

fred = FrederickTheFrog.new
class << fred
  def hoppityhop
    puts("Ribburrt")
  end
end

It’s as though when you create a new instance, a new class is created that sits between the instance and the original class.

(For efficiency reasons, the Ruby interpreter doesn’t really create the class unless you actually need it, but that’s just an implementation detail. See rb_singleton_class in class.c for details.) 
class JustForFred < FrederickTheFrog
end

fred = JustForFred.new

(For whatever reason, in Ruby methods are defined for classes, not for objects. However, since each object has its own personal hidden class, it doesn’t matter.)

Matz calls obj a “singleton class”, but some people call by names such as “meta-class” and “idioclass”.

One argument against the term “singleton class” is that it is also used in some other language communities to mean a class which only ever has one instance. (For example, in the original book on Design Patterns.)

Matz: “Interestingly, I started to use the term before the book was published in 1995. Sad coincidence.”

He added, “Until we find a better term. I don’t think other terms proposed such as “exclusive class” are better. I assume Ruby users smart enough to deal with them by context until the time.”

Net::HTTP::Proxy using one or more proxies

Botp Peña wondered, “is possible to use multiple proxies in Net::HTTP::Proxy?”

Minero Aoki: “In a word, No. You must use multiple Net::HTTP objects explicitly.”

Cows and Bulls (#32)

The following Ruby Quiz was created by Pat Eyler.

“My kids like to play a variant of “Cows and Bulls” when we’re driving. One of them (the server, to use a computing term—you’ll see why in a minute) will think of a word (we usually play with either three or four letters), and the other (the client) will try to guess it. With each guess, the server will respond with the number of ‘cows’ (letters in the word, but not in the right place) and bulls (letters in the correct place in the word).”

Write a client and server to play this game.

We need a comprehensive test suite

Daniel Berger exclaimed “Matz’s announcement of 1.8.3 beta 1 reminds me of something. We need a test suite. A large, comprehensive test suite. Written using test-unit. And we need it NOW.”

Eric Hodel said that it should be based on Rubicon, a test suite originally written by Dave and Andy of PragmaticProgrammer fame. It needs some work to be updated to Ruby 1.8, but has “75% of the work done for you already, has nice reports, and has many of the platform/version differences spelled out.”

Chad Fowler recalled that Matz had agreed in the past to the idea of including Rubicon with Ruby. It just requires someone with enough time and motivation to add it to the CVS tree in a clean way.

Query about the top level object

In a related thread, Gavri Fernandez asked about methods that are defined at the “top-level”.

He quoted the first edition of the Pickaxe,

At the top level, we’re executing code in the context of some predefined object. When we define methods, we’re actually creating (private) singleton methods for this object.

Gavri wasn’t sure this was true, he’d read somewhere that they were defined as private methods of Object, and his testing appeared to show this was the case.

def whoa
  puts "in whoa" 
end
Object.new.private_methods.include?('whoa')   # true
This means that every Ruby object then has a private method called whoa. An alternative is to define the method in the Kernel module. 
module Kernel
  def whoa
    puts "in whoa" 
  end
end

Object.new.private_methods.include?('whoa')   # false

whoa()    # prints "in whoa"

There is a bit of a confusion, since if you look at self at the top-level, you see it is an instance of Object called main.

(Warnng: Be careful about experimenting with this sort of thing in irb. Because of the way irb is implemented, visibility – public, private etc. – can be different to usual.)

Christoph explained that “Defining a (private) method at the “top” scope is equivalent to defining a private method at the scope of the class Object.”

rbtree in the stdlib

Martin DeMello proposed in RCR-306 that rbtree be included in the Ruby standard library, and also that PriorityQueue and other such classes be added.

rbtree is a library providing a Red/Black Tree implementation for Ruby. There are many algorithms where a balanced tree structure is useful, for example where you need a Set of Arrays. Computing a hash in that case may be a relatively slow operation.

New Releases

Classifier 1.3.0: New Summary feature and no dependency on external c-libraries

Lucas Carlson announced that Classifier is now available as a pure-Ruby library, as well as a version that uses the GSL library.

A new method String#summary was also added. This uses Classifier to automatically summarise a block of text by guessing what the most important sentences are.

Ruby/Odeum 0.3.1 Pre-Release

Zed A. Shaw announced a pre-release of Ruby/Odeum, a binding to the QDBM Odeum inverted index library. (Useful for implementing a search engine.)

The major new addition is a boolean expression query language, allowing you to search for e.g. "Zed & Shaw ! (Frank Blank)". Performance has also been improved in some circumstances.

HighLine 0.5

See also HighLine 0.3.0—Now with ANSI colors! and HighLine 0.4.0.

James Edward Gray II released new versions of HighLine, a library to make it easy to write an application that takes input from the console.

0.3 added support for colours in the output, whitespace handlng, improved type conversions, and single-character input.

0.4 added word wrapping and “paged printing” output.

0.5 brought an “echo setting (for passwords)”, confirmation questions and case-sensitivity settings.

Packgen 0.1

Ghislain Mary released Packgen, a “simple network packet generator handling diffserv markers, useful for testing network bandwidth and QoS.”

color-tools 1.1.0

Austin Ziegler updated his color-tools package. This library is used to manipulate RGB and CMYK colours.

It can now read GIMP colour palette definition files.

session-2.4.0

Ara.T.Howard added the ability to specify stdin for Session::Bash and Session::Sh.

Session is a set of classes for “driving external progams via pipes.”

Ruby Editor Plugin for jEdit 0.6.1 - method completion release II

Rob released a new version of the Ruby Editor Plugin for jEdit. The UI for method completion was improved. An integrated Ruby documentation viewer was also added.

He later asked for feedback on how users feel about the method completion.

There was discussion in the thread announcing 0.6.0.

Subsequently, Ruby Editor Plugin for jEdit – release 0.6.5 was posted, adding class hierachy information to the documentation viewer.

KirbyBase 2.2

Jamey Cribbs made some major internal changes to KirbyBase, a simple pure-Ruby database management system that stores its data in plain-text files.

The design of the code is now much cleaner. Some functional changes were also made.

Pages-BibTeX

Tom Counsell announced a script to help users of iWord on MacOS X. It fixes bibliographies in the Apple Pages word-processor.

sldb-0.1.0

Ara.T.Howard announced “sldb is a multi-thread, multi-process, and nfs safe abstraction of sqlite databases.” It deals with locking and retrying transactions so you don’t have to.

He had earlier introduced sldb-0.0.0.

An extension to Rational - friendlier with Floats and Strings

Dave recalled a recent thread about converting a Float to a Rational, for example 1.5 to 3/2.

He took a look at how Python handled this, and wrote some new methods for Ruby in a similar spirit.

For example, 1.5.to_r returns Rational(3, 2). Other methods added include Rational#approximate, to simplify a Rational, to +/- some error.

Rant 0.3.6

Stefan Lang improved Rant, a “flexible build tool written entirely in Ruby, similar to Rake”.

Generated files are now automatically cleaned up, and “constraining variables” and “directed rules” were added.

Pimki 1.7

Assaph Mehr announced Pimki 1.7.092, which he hopes will be the last release before Pimki2.

Bugs were fixed and features added.

webgen 0.3.4

Thomas Leitner improved webgen, a tool to generate web pages from page description and template files.

ERB can now be used, file handling has been enhanced, bugs fixed and other features added.

MuraveyWeb 0.2.1 -- Ruby on Rails CMS

Dmitry V. Sabanin put out a bugfix release for the MuraveyWeb content management system. He quickly made an “Emergency Release” of 0.2.2 to fix a bug in 0.2.1 that made SimpleFolders unusable.

Ruby-GetText-Package-0.9.0

Masao Mutoh’s Ruby-GetText-Package was updated. It is a Native Language Support Library Tool.

CGI and ERB are now supported.

Updateable 0.0.3

John W. Long made the first public release of a small module that allows you to update the attributes of an object from a Hash.

RubyInline 3.3.1 Released

Ryan Davis fixed some bugs in RubyInline, a library that makes it easy to embed C and C++ code within a Ruby source file.

Webstar Tools 0.5.0 Released!

Zach Dennis posted the latest iteration of his set of command-line utilities for the WebSTAR V Internet Server on MacOS X.

Transaction::Simple 1.3.0

Austin Ziegler announced the latest release of Transaction::Simple, a library allowing you to easily use in-memory transactions. “This is to allow “test” changes to be made to an object before making the changes permanent.”

This version adds “transaction groups”, allowing you to have a single transaction for multiple objects.

John Lam said “Wow wow wow! This is so massively cool.”

Ri18n 0.0.3 Ruby application internationalization library

In a related release, dm1 laid out Ri18n-0.0.3, a library whose goals are similar to Ruby-GetText-Package – to help internationalisation of Ruby programs.

RJournal 0.1.1

Vincent Foley released his first open source project, RJournal, a simple LiveJournal client. He plans to add a Fox GUI to it in the future.

traits-0.0.0 and 0.1.0

Ara.T.Howard announced the first version of traits (really, just the renaming of attributes.rb). It provides “a better set of attr_* methods”.

trails-0.1.0 was also released.

Production Log Analyzer 1.2.0

Eric Hodel released a new version of his Production Log Analyzer, used to determine which pages on a dynamic website are the slow ones.

This version includes a new time summary, plus support for sending email with sendmail.