* 1 Fedora Weekly News Issue 265
o 1.1 Announcements
+ 1.1.1 Fedora Announcement News
# 1.1.1.1 Infrastructure Outage Notification: 2011-03-02
1200 UTC -> 1500 UTC
# 1.1.1.2 Updated: Outage: Ibiblio/ipv6 servers -
2011-03-02 14:00 UTC
* 1.1.1.2.1 Reason for outage
* 1.1.1.2.2 Contact Information
+ 1.1.2 Fedora Events
# 1.1.2.1 Upcoming Events (Dec 2010 - Feb 2011)
# 1.1.2.2 Past Events
# 1.1.2.3 Additional information
o 1.2 Fedora In the News
+ 1.2.1 Who Contributes the Most to LibreOffice? (Linux Journal)
+ 1.2.2 Fedora 15 alpha delayed - Btrfs may be default in 16 (H
Online)
+ 1.2.3 Beyond FUDCon with Robyn Bergeron, Fedora Program
Manager (Linux Magazine)
o 1.3 Ambassadors
+ 1.3.1 Welcome New Ambassadors
+ 1.3.2 Summary of traffic on Ambassadors mailing list
+ 1.3.3 Summary of events reported on Ambassadors mailing list
+ 1.3.4 Summary of traffic on FAmSCo mailing list
o 1.4 QualityAssurance
+ 1.4.1 Test Days
+ 1.4.2 Fedora 15 Alpha preparation
+ 1.4.3 Bodhi improvements
+ 1.4.4 FreeIPA Test Day problems and proposals
+ 1.4.5 Complications for Delta ISO users
+ 1.4.6 IPv6 testing
+ 1.4.7 Using abrt during Test Days
o 1.5 Security Advisories
+ 1.5.1 Fedora 14 Security Advisories
+ 1.5.2 Fedora 13 Security Advisories
o 1.6 LATAM Fedora!
+ 1.6.1 Ruby Capítulo 1: El primer contacto
# 1.6.1.1 Aprovechando el espacio
# 1.6.1.2 Los "Hola mundo"
* 1.6.1.2.1 holamundo.rb
* 1.6.1.2.2 holamundo.rb
# 1.6.1.3 Ruby es un lenguaje de programación orientado a
objetos
# 1.6.1.4 Pero no necesito clases
# 1.6.1.5 Clases base
* 1.6.1.5.1 Cadenas de caracteres, String
* 1.6.1.5.2 Arreglos, Array
* 1.6.1.5.3 Arreglos indexados arbitrariamente, Hash
* 1.6.1.5.4 Recapitulación rápida, los objetos y
sus métodos, ¿documentación?
# 1.6.1.6 Ruby es dinámico ¿ 2 + 2 = 4 ?
* 1.6.1.6.1 fixnum_mod.rb
* 1.6.1.6.2 Y ahora ejecutamos nuestro programa:
# 1.6.1.7 Estructuras de control
# 1.6.1.8 Lazos e iteradores
* 1.6.1.8.1 Lazo con for y loop:
- Fedora Weekly News Issue 265 -
Welcome to Fedora Weekly News Issue 265[1] for the week ending March 2, 2011.
What follows are some highlights from this issue.
Our issue kicks off with a couple outage announcements from this past week,
followed by three articles 'In the News', including an interview with Fedora
Program Manager, Robyn Bergeron. In Ambassador news, summaries of traffic on
the Ambassador and FAmSCo lists, and QA brings us a whole slew of Test Day
details over the next few weeks, Fedora 15 prep and bodhi improvements.
Security Advisories keeps us updated with security-related patches released
this past week. We're also very pleased this week to kick off our foreign
language content initiative, which developed out of FUDCon Tempe, with a new
Latin American beat, all in Spanish. To start off, we have part one of a Ruby
on Fedora primer, contributed by Guillermo Gómez, a Fedora Ambassador in
Venezuela. If you would like to contribute Fedora-related content in your
language, please send a note to the editors!
An audio version of some issues of FWN - FAWN - are available! You can listen
to existing issues[2] on the Internet Archive. If anyone is interested in
helping spread the load of FAWN production, please contact us!
If you are interested in contributing to Fedora Weekly News, please see our
'join' page[3]. We welcome reader feedback: [email protected]
FWN Editorial Team: Pascal Calarco, Adam Williamson
1. http://fedoraproject.org/wiki/FWN/Issue265
2. http://www.archive.org/search.php?query=subject%3A%22FWN%22
3. http://fedoraproject.org/wiki/NewsProject/Join
-- Announcements --
In this section, we cover announcements from the Fedora Project, including
general announcements[1], development announcements[2] and Events[3].
Contributing Writer: Rashadul Islam
1. http://lists.fedoraproject.org/pipermail/announce/
2. http://lists.fedoraproject.org/pipermail/devel-announce/
3. http://fedoraproject.org/wiki/Events
--- Fedora Announcement News ---
The announcement list is always exclusive for the Fedora Community. Please,
visit the past announcements at[1]
1. https://admin.fedoraproject.org/mailman/listinfo/announce
---- Infrastructure Outage Notification: 2011-03-02 1200 UTC -> 1500 UTC ----
Stephen John Smoogen on Tue Mar 1 20:13:07 UTC 2011 announced[1],
"Tomorrow the services at ibiblio will be moved to a new physical location
* ibiblio01.fedoraproject.org
* app05
* backup02
* ns02
* proxy04
* smtp-mm03
* torrent01"
1. http://lists.fedoraproject.org/pipermail/announce/2011-March/002928.html
---- Updated: Outage: Ibiblio/ipv6 servers - 2011-03-02 14:00 UTC ----
Stephen John Smoogen on Tue Mar 1 22:09:31 UTC 2011 announced[1],
"Outage: Ibiblio/ipv6 servers - 2011-03-02 14:00 UTC
There will be an outage starting at UTC, 2011-03-02 14:00 which will last
approximately 4 hours.
To convert UTC to your local time, take a look at[2] or run:
date -d '2011-03-02 14:00 UTC'
----- Reason for outage -----
metalabs is moving facilities and needs for our collocated server to move with
them. Systems will be down and getting new IP addresses with the move. [3]
----- Contact Information -----
Please join #fedora-admin in irc.freenode.net or respond to this email to track
the status of this outage."
1. http://lists.fedoraproject.org/pipermail/announce/2011-March/002929.html
2. http://fedoraproject.org/wiki/Infrastructure/UTCHowto
3. https://fedorahosted.org/fedora-infrastructure/ticket/2651
--- Fedora Events ---
The purpose of event is to build a global Fedora events calendar, and to
identify responsible Ambassadors for each event. The event page is laid out by
quarter and by region. Please maintain the layout, as it is crucial for budget
planning. Events can be added to this page whether or not they have an
Ambassador owner. Events without an owner are not eligible for funding, but
being listed allows any Ambassador to take ownership of the event and make it
eligible for funding. In plain words, Fedora events are the exclusive and
source of marketing, learning and meeting all the fellow community people
around you. So, please mark your agenda with the following events to consider
attending or volunteering near you!
---- Upcoming Events (Dec 2010 - Feb 2011) ----
* North America (NA)[1]
* Central & South America (LATAM): [2]
* Europe, Middle East, and Africa (EMEA)[3]
* India, Asia, Australia (India/APJ)[4]
1. http://fedoraproject.org/wiki/Events#FY12_Q1_.28March_2011_-_May_2011.29
2. http://fedoraproject.org/wiki/Events#FY12_Q1_.28March_2011_-_May_2011.29_2
3. http://fedoraproject.org/wiki/Events#FY12_Q1_.28March_2011_-_May_2011.29_3
4. http://fedoraproject.org/wiki/Events#FY12_Q1_.28March_2011_-_May_2011.29_4
---- Past Events ----
Archive of Past Fedora Events[1]
1. http://fedoraproject.org/wiki/FedoraEvents/PastEvents
---- Additional information ----
* Reimbursements -- reimbursement guidelines.
* Budget -- budget for the current quarter (as distributed by FAMSCo).
* Sponsorship -- how decisions are made to subsidize travel by community
members.
* Organization -- event organization, budget information, and regional
responsibility.
* Event reports -- guidelines and suggestions.
* LinuxEvents -- a collection of calendars of Linux events.
-- Fedora In the News --
In this section, we cover news from the trade press and elsewhere that is
re-posted to the Fedora Marketing list[1].
http://fedoraproject.org/wiki/Marketing
Contributing Writer: Pascal Calarco
1. http://lists.fedoraproject.org/pipermail/marketing/
--- Who Contributes the Most to LibreOffice? (Linux Journal) ---
Rahul Sundaram forwarded[1] an article from Linux Journal noting contributions
to LibreOffice:
"Bosdonnat began tracking line contributions in the middle of September 2010
with the original 14 contributions being made by Oracle. Oracle actually
contributes code to OpenOffice.org, and then LibreOffice merges those changes,
thus resulting in Oracle's contributions to the new fork. These 112
contributions have continued throughout development, but are dwarfed by the
contributions of new developers."
These contributions make up well over half of the total new changes found in
LibreOffice as of mid-February. Weekly contributions in this area have averaged
between 20 and 30 with a total number of 517 line contributions.
Red Hat, who also contributed to OpenOffice.org, has chipped in as well. With
usually two contributions per week, Red Hat developers have provided 39 patches
since the fork."
The full article is available[2].
1. http://lists.fedoraproject.org/pipermail/marketing/2011-March/013722.html
2. http://www.linuxjournal.com/content/who-contributes-most-libreoffice
--- Fedora 15 alpha delayed - Btrfs may be default in 16 (H Online) ---
Rahul Sundaram forwarded[1] an an article in The H Online about the decision to
push back Fedora 15 alpha:
"The Fedora project has postponed the release of the first and only alpha
version of Fedora 15, originally scheduled for 1 March, by a week. This was
due, at least in part, to a bug in X Server that occurred in connection with
keyboard layouts for such languages as German or French and prevented users
from successfully logging into GDM. Subsequent milestones in the release
schedule for Fedora 15 remain unaffected at present, and the final release is
still scheduled for 10 May.
The fifteenth Fedora release is currently planned to be the first version that
won't require a special boot parameter to be submitted to the installer in
order to format a storage device with the experimental Btrfs file system. Red
Hat employee Josef Bacik, who is heavily involved in the development of Btrfs,
has now proposed on the project's most important developer mailing list that
Btrfs should be made the default file system in Fedora 16, which is expected in
late October or early November"
The full post is available[2].
1.
http://lists.fedoraproject.org/pipermail/marketing/2011-February/013713.html
2.
http://www.h-online.com/open/news/item/Fedora-15-alpha-delayed-Btrfs-may-be-default-in-16-1198065.html
--- Beyond FUDCon with Robyn Bergeron, Fedora Program Manager (Linux Magazine)
---
Rahul Sundaram forwarded[1] another article highlighting Fedora community
leaders, this with Robyn Bergeron, who remarked:
"I personally would love to see more folks getting involved in areas that don't
necessarily require coding skills. I think that there is enormous room for
growth and contribution in these areas, and there are plenty of Linux
enthusiasts out there who have the skills and imagination to make great
contributions in these places."
The full article is available[2]
-- Ambassadors --
This section covers the news surrounding the Fedora Ambassadors Project[3].
Contributing Writer: Sankarshan Mukhopadhyay
1.
http://lists.fedoraproject.org/pipermail/marketing/2011-February/013714.html
2.
http://www.linux-magazine.com/Online/News/Beyond-FUDCon-with-Robyn-Bergeron-Fedora-Program-Manager
3. http://fedoraproject.org/wiki/Ambassadors
--- Welcome New Ambassadors ---
This week the Fedora Ambassadors Project had no new members joining.
--- Summary of traffic on Ambassadors mailing list ---
Pierros Papadeas posted [1] about Ambassador SOPs [2] on which FAmSCo has been
working.
Clint Savage suggested [3] attending the FAD at SCaLE this year specifically
mentioning the Sysadmin Study Group
Buddhika Kurera informed [4] that the order for the FAm T-shirts [5] had been
placed and expected delivery is around end of March (impacted by the orders
around the ICC Cricket World Cup)
Neville A. Cross asked [6] if any other Fedora Project participants would be
attending PyCon from 2011-03-08 till 2011-03-13. Mark McIntyre responded [7]
and provided his plans. Max Spevack suggested [8] creating an Event page and
also posting to devel at lists.fedoraproject.org. The page [9] was created by
Mark McIntyre
Pierre-Yves Chibon posted [10] the translated annual report [11] for Fedora-Fr,
the French speaking NPO.
David Ramsey provided prior notice [12] about Fedora 15 Test Days [13] coming up
David Ramsey posted [14] the draft Agenda [15] of the APAC meeting on 2011-03-05
Caius Chance informed [16] about having around 700 F14 LiveCDs with him at
Brisbane and wanted to get them to Fedora Ambassadors in APAC soonest. The
thread [17] had requests from Ambassadors who wanted the CDs.
Christoph Wickert announced [18] that the Trac instance used by the Fedora
Board [19] was open for ticket submissions by all FAS account holders.
Christoph Wickert provided an update [20] on the Fedora 14 media for EMEA
Max Spevack posted [21] an initial announcement of the Finance SIG [22]
David Ramsey posted [23] about Summer Coding Ideas for 2011 [24]
Larry Cafiero posted [25] Meeting Minutes from FAmNA meeting on 2011-03-01[26]
1.
http://lists.fedoraproject.org/pipermail/ambassadors/2011-February/017066.html
2. https://fedoraproject.org/wiki/Ambassadors_SOPs
3.
http://lists.fedoraproject.org/pipermail/ambassadors/2011-February/017071.html
4.
http://lists.fedoraproject.org/pipermail/ambassadors/2011-February/017073.html
5. https://fedoraproject.org/wiki/User:Bckurera/APAC-shirts
6.
http://lists.fedoraproject.org/pipermail/ambassadors/2011-February/017077.html
7.
http://lists.fedoraproject.org/pipermail/ambassadors/2011-February/017090.html
8.
http://lists.fedoraproject.org/pipermail/ambassadors/2011-March/017099.html
9. https://fedoraproject.org/wiki/FedoraEvents/PyCon_2011
10.
http://lists.fedoraproject.org/pipermail/ambassadors/2011-February/017078.html
11. https://fedoraproject.org/wiki/Fedora-Fr_annual_report_2010
12.
http://lists.fedoraproject.org/pipermail/ambassadors/2011-February/017079.html
13. https://fedoraproject.org/wiki/Category:Fedora_15_Test_Days
14.
http://lists.fedoraproject.org/pipermail/ambassadors/2011-February/017081.html
15. https://fedoraproject.org/wiki/Meeting:APAC_Ambassadors_2011-03-05#Agenda
16.
http://lists.fedoraproject.org/pipermail/ambassadors/2011-February/017083.html
17.
http://lists.fedoraproject.org/pipermail/famsco/2011-February/thread.html#687
18.
http://lists.fedoraproject.org/pipermail/ambassadors/2011-February/017094.html
19. https://fedorahosted.org/board/newticket
20.
http://lists.fedoraproject.org/pipermail/ambassadors/2011-February/017095.html
21.
http://lists.fedoraproject.org/pipermail/ambassadors/2011-March/017098.html
22.
http://lists.fedoraproject.org/pipermail/advisory-board/2011-March/010523.html
23.
http://lists.fedoraproject.org/pipermail/ambassadors/2011-March/017102.html
24. https://fedoraproject.org/wiki/Summer_coding_ideas_for_2011
25.
http://lists.fedoraproject.org/pipermail/ambassadors/2011-March/017105.html
26.
http://meetbot.fedoraproject.org/fedora-meeting/2011-03-02/fedora-meeting.2011-03-02-02.02.html
--- Summary of events reported on Ambassadors mailing list ---
No event reports were posted to the Ambassadors mailing list.
--- Summary of traffic on FAmSCo mailing list ---
Caius Chance informed [1] about having around 700 F14 LiveCDs with him at
Brisbane and wanted to get them to Fedora Ambassadors in APAC soonest.
Max Spevack posted [2] an initial announcement of the Finance SIG [3]
1. http://lists.fedoraproject.org/pipermail/famsco/2011-February/000687.html
2. http://lists.fedoraproject.org/pipermail/famsco/2011-March/000688.html
3.
http://lists.fedoraproject.org/pipermail/advisory-board/2011-March/010523.html
-- Quality Assurance --
In this section, we cover the activities of the QA team[1]. For more
information on the work of the QA team and how you can get involved, see the
Joining page[2].
Contributing Writer: Adam Williamson
1. http://fedoraproject.org/wiki/QA
2. http://fedoraproject.org/wiki/QA/Join
--- Test Days ---
Thursday 2011-02-17 was Xfce 4.8[1] Test Day[2]. The event was well organized
by the Xfce team, and a dedicated group of testers was able to expose some
important bugs to be fixed.
The week of 2011-02-21 saw the traditional Graphics Test Week. Adam Williamson
posted a full recap of the event to the mailing list[3]. He noted that
participation was up again compared to the Fedora 14 events and that some
important testing had been carried out, but also noted a worrying trend in
status of bugs from previous events, with many bugs reported during the Fedora
13 and 14 events remaining unfixed. He promised to investigate the causes of
this.
This week (and next Tuesday!) is internationalization and localization Test
Week, and Adam Williamson put up a blog post[4] explaining the three Test Days
this includes: the Anaconda i18n and l10n Test Day on 2011-03-01[5], the
desktop i18n Test Day on 2011-03-03[6] and the desktop l10n Test Day on
2011-03-08[7]. All these events are very important to ensure that
non-US-English-speaking users of Fedora get a great experience with Fedora 15.
Thursday 2011-03-10 will be the second of three planned GNOME 3 Test Days[8],
where we'll continue to work with the GNOME team to test GNOME 3.0 and its
integration with Fedora 15 as rigorously as we can before the final release of
both. We'll be repeating the tests from the previous event to see how things
have progressed, and also running some new tests which have been added for this
event. As before, this is a very important event for both Fedora and GNOME and
affects most Fedora users, so if you have a few minutes to spare, please come
along and help testing. Once again, live images will be available to make it
easier to test, and we'll have a new process in place for reporting crasher
bugs without the trouble of trying to install debuginfo packages on a live
image!
1. http://fedoraproject.org/wiki/Features/Xfce48
2. http://fedoraproject.org/wiki/Test_Day:2011-02-17_Xfce
3.
http://lists.fedoraproject.org/pipermail/test-announce/2011-March/000200.html
4.
http://www.happyassassin.net/2011/02/28/internationalization-and-localization-test-week-this-week/
5. http://fedoraproject.org/wiki/Test_Day:2011-03-01_L10n_i18n_Installation
6. http://fedoraproject.org/wiki/Test_Day:2011-03-03_I18n_Desktop
7. http://fedoraproject.org/wiki/Test_Day:2011-03-08_L10n_Desktop
8. http://fedoraproject.org/wiki/Test_Day:2011-03-10_GNOME3_Beta
--- Fedora 15 Alpha preparation ---
The QA team has been busy over the last two weeks validating the Fedora 15
Alpha release, with TC2[1], RC1[2], and RC2[3] candidate builds being posted
and tested. As always, the whole team chipped in with the all-important
testing. In the end the RC1 image was not accepted and the release delayed for
a week[4] due to a significant bug with many non-English keyboard layouts which
was exposed during the testing. With this bug fixed, the RC2 image was accepted
as gold at the go/no-go meeting of 2011-03-02[5].
--- Bodhi improvements ---
At the weekly meeting of 2011-02-28[6], Luke Macken announced that
package-specific test case integration into Bodhi is now live, meaning that
packages which have test cases associated with them according to the package
test plan SOP[7] will now have the test cases displayed in Bodhi when an update
for the package is under review. Also going live in the new Bodhi release are
the improvements to the automated messages Bodhi sends to Bugzilla when an
update's status changes, improvements discussed in previous issues of this
newsletter.
1.
http://lists.fedoraproject.org/pipermail/test-announce/2011-February/000186.html
2.
http://lists.fedoraproject.org/pipermail/test-announce/2011-February/000190.html
3.
http://lists.fedoraproject.org/pipermail/test-announce/2011-February/000194.html
4.
http://lists.fedoraproject.org/pipermail/devel-announce/2011-February/000759.html
5.
http://meetbot.fedoraproject.org/fedora-meeting/2011-03-02/fedora_15_alpha_gono-go_meeting.2011-03-02-22.00.html
6. http://fedoraproject.org/wiki/QA/Meetings/20110228
7. http://fedoraproject.org/wiki/QA:SOP_package_test_plan_creation
--- FreeIPA Test Day problems and proposals ---
Dmitri Pal posted a comment to the FreeIPA Test Day trac ticket[1] noting that
he was unhappy with the way the event had turned out. Adam Williamson, James
Laska and Jóhann Guðmundsson joined in with suggestions to try and learn from
this experience. Dmitri is considering re-running the event with some tweaks.
1. http://fedorahosted.org/fedora-qa/ticket/163#comment:10
--- Complications for Delta ISO users ---
Andre Robatino provided some detailed information[1] on what a change to the xz
compression scheme would mean for users of DeltaISOs. In a nutshell, users
trying to use Fedora 14 -> Fedora 15 DeltaISOs will need to use a workaround,
detailed in the post, if applying the ISO on a Fedora 14 system. Andre followed
up later with a refinement of the workaround[2].
1. http://lists.fedoraproject.org/pipermail/test/2011-February/097009.html
2. http://lists.fedoraproject.org/pipermail/test/2011-February/097284.html
--- IPv6 testing ---
A.J. Werkman provided a recap of some very solid testing he had performed on
Fedora's out-of-the-box IPv6 capabilities[1]. He identified some significant
problems and reported them as bugs, including anaconda refusing to work without
an IPv4 DHCP lease, and Fedora's Bugzilla not being available in the IPv6
domain.
1. http://lists.fedoraproject.org/pipermail/test/2011-February/097153.html
--- Using abrt during Test Days ---
A thread[1] started by Mike Cloaked highlighted the issue of abrt being
difficult or impossible to use successfully from live images (such as during
Test Days), in large part due to the size of debuginfo packages. Adam
Williamson pointed out[2] that the abrt team's retrace server project[3] would
be a perfect solution for this, but noted that he had not yet tested using it.
When he did, it seemed not yet to be ready for Fedora 15[4]. Jiri Moskovc said
that the Fedora 15 support would soon be available[5].
1. http://lists.fedoraproject.org/pipermail/test/2011-February/097271.html
2. http://lists.fedoraproject.org/pipermail/test/2011-February/097289.html
3. http://fedoraproject.org/wiki/Features/RetraceServer
4. http://lists.fedoraproject.org/pipermail/test/2011-February/097299.html
5. http://lists.fedoraproject.org/pipermail/test/2011-February/097314.html
-- Security Advisories --
In this section, we cover Security Advisories from fedora-package-announce from
the past week.
http://lists.fedoraproject.org/pipermail/package-announce
Contributing Writer: Pascal Calarco
--- Fedora 14 Security Advisories ---
none
--- Fedora 13 Security Advisories ---
* ruby-1.8.6.420-2.fc13 -
http://lists.fedoraproject.org/pipermail/package-announce/2011-March/054436.html
* abcm2ps-5.9.21-1.fc13 -
http://lists.fedoraproject.org/pipermail/package-announce/2011-March/054424.html
* telepathy-glib-0.11.16-2.fc13 -
http://lists.fedoraproject.org/pipermail/package-announce/2011-March/054409.html
* telepathy-gabble-0.10.5-1.fc13 -
http://lists.fedoraproject.org/pipermail/package-announce/2011-March/054408.html
-- LATAM Fedora! --
LATAM Fedora is a regular column of Spanish language contributions around open
source software. It is our first expansion into incorporating foreign language
content into FWN.
This week's contribution is from Guillermo Gómez, a primer on Ruby. Enjoy!
--- Ruby Capítulo 1: El primer contacto ---
"Yo quería un lenguaje de programación más poderoso que Perl y más orientado a
objetos que Python. Entonces me acordé de mi viejo sueño y decidí diseñar mi
propio lenguaje. Al principio estuve jugando con él en el trabajo. Gradualmente
creció lo suficiente como para remplazar a Perl. Lo llamé Ruby en honor a esa
piedra preciosa roja y lo liberé al público en 1995."
Yukihiro Matsumoto, a.k.a. ``Matz Japan, October 2000
---- Aprovechando el espacio ----
Para comenzar en Fedora con Ruby vamos instalar lo mínimo necesario y sin
perder mucho espacio dando vueltas con teoría y opiniones, directo al grano.
Abra una sesión de emulación de terminal preferida y siga las siguientes
instrucciones para instalar. En la medida que desarrollemos esta columna
dedicada a Ruby, entonces iremos descubriendo el poder y flexibilidad de Ruby.
$ su -
<contraseña de root>
# yum install ruby ruby-rdoc ruby-ri
Para el editor, hay muchas opciones, mi editor de preferencia es Vim , pero
puede usar el de su preferencia, intente usar alguno que pueda resaltar
sintaxis Ruby como mínimo. Puede escoger desde entornos tan complejos y
completos como Eclipse, hasta editores de escritorio GUI como Gedit, o simples
en consola como nano o complejos y sofisticados como Vim y Emacs.
---- Los "Hola mundo" ----
La primera forma interactiva simple de ejecutar comandos Ruby es simplemente
usar el intérprete, simplemente ejecute el intérprete, ingrese los comandos y
termine presionando Ctrl-D para indicarle al intérprete que la entrada de
comandos ha finalizado:
$ ruby
puts "Hola Mundo"
<Ctrl-D>
Hola Mundo
La segunda forma interactiva es con irb. irb es el acrónimo para Interactive
Ruby. irb es un shell Ruby, es decir, es un espacio donde puede evaluar su
código al instante. En próximas ediciones iremos desarrollando más el tema de
irb, por ahora simplemente invoque a irb e intente:
$ irb
irb(main):001:0> puts "Hola Mundo"
Hola Mundo
=> nil
irb(main):002:0>exit
$
Si lo que quiere es crear un programa Ruby que nos imprima "Hola Mundo" en la
salida del monitor, lance su editor e incluya el siguiente código fuente en un
archivo denominado holamundo.rb., guarde y salga de su editor.
----- holamundo.rb -----
1 puts "Hola Mundo"
Para ejecutar simplemente pásale al intérprete Ruby el archivo como argumento.
[gomix@fricky capitulo_1]$ ruby holamundo.rb
Hola Mundo
También puede usar el método "shebang" y convertir el archivo fuente Ruby en
ejecutable del sistema, edite su holamundo.rb para que luzca como se muestra en
el listado a continuación.
----- holamundo.rb -----
1 #!/usr/bin/ruby
2
3 puts "Hola Mundo"
[gomix@fricky capitulo_1]$ chmod +x holamundo.rb
[gomix@fricky capitulo_1]$ ./holamundo.rb
Hola Mundo
Existe la forma de pasarle directamente código Ruby al intérprete sin apoyo de
archivos o programas adicionales y sin entrar en modo interactivo.
$ ruby -e 'puts "Hola Mundo"'
Hola Mundo
---- Ruby es un lenguaje de programación orientado a objetos ----
Todo lo que usted manipula en Ruby es un objeto, y los resultados de dichas
manipulaciones a su vez, también son objetos. Cuando usted escribe código
orientado a objetos normalmente está modelando conceptos del mundo real en su
código. Típicamente durante este proceso de modelado usted descubrirá
categorías de cosas que necesitan ser representadas en código. En un
reproductor de música el concepto de "canción" puede ser una de esas
categorías. En Ruby usted define una clase para representar cada una de esas
entidades. Una clase es una combinación de estado, por ejemplo el nombre de la
canción, y métodos que usan dicho estado, por ejemplo para reproducir la
canción.
Una vez que tiene dichas clases usted creará instancias de dicha clase. Para el
reproductor de música que contiene la clase Cancion usted terminará teniendo
instancias separadas independientes para canciones populares como "Todo o
nada", "Canción para un amigo", "Amanecer llanero", y por el estilo. La palabra
objeto e instancia son intercambiables. En Ruby para crear dichas instancias u
objetos, se debe llamar a un método constructor de la clase, el método
constructor estandar se llama new.
1 cancion1 = Cancion.new("Amanecer llanero")
2 cancion2 = Cancion.new("Todo o nada")
Estas instancias son derivadas de la misma clase pero tienen características
únicas. Primero, cada objeto tiene un object_id único. Segundo, usted puede
definir variables de instancia, variables con valor que son únicos para cada
instancia. Estas variables de instancia mantienen el estado del objeto.
Igualmente puede definir métodos de instancia para acceder y/o alterar el
estado del objeto, es decir, acceder y/o alterar las variables de instancia.
Rápidamente definamos nuestra clase Cancion. Ruby se puede leer fácilmente.
1 class Cancion
2 def titulo
3 @titulo
4 end
5
6 def titulo=(titulo_de_la_cancion)
7 @titulo = titulo_de_la_cancion.to_s
8 end
9 end
Claramente podemos ver y leer que hemos definido la clase de nombre Cancion con
dos métodos de instancia, titulo y titulo=. La variable de instancia se
representa en @titulo , con la notación de nombre de variable en minúscula
precedida del símbolo @ .
Note la indentación que hemos implementado para representar la estructura, dos
espacios es cómun entre los Rubyeros (me gusta llamarlos así).
Es evidente que la plabra clave class establece el inicio de un bloque que se
cierra con end para definir una clase con nombre, en este ejemplo Cancion.
Dentro de dicha estructura también podemos identificar claramente la palabra
clave def que igualmente define bloques que se cierran también con la palabra
clave end. def define dos métodos de instancia en este ejemplo. Hablaremos más
de def de forma recurrente en muchas ediciones de esta columna.
Podemos probar nuestra clase en irb fácilmente, por ahora tipee con cuidado
para no equivocarse, luego le ofreceré más técnicas irb.
1 $ irb
2 >> class Cancion
3 >> def titulo
4 >> @titulo
5 >> end
6 >> def titulo=(titulo_de_la_cancion)
7 >> @titulo = titulo_de_la_cancion.to_s
8 >> end
9 >> end
10 => nil
11 >> cancion1 = Cancion.new
12 => #<Cancion:0xb76e25c8>
13 >> cancion1.titulo="Alma llanera"
14 => "Alma llanera"
15 >> cancion1.titulo
16 => "Alma llanera"
---- Pero no necesito clases ----
También se puede usar Ruby del modo procedimental, funcional, sin necesidad de
crear (explícitamente) clases y objetos.
1 $ irb
2 >> 2 + 2
3 => 4
Pero igual note que estamos trabajando con objetos de alguna clase, en nuestro
ejemplo Fixnum.
1 >> 2.class
2 => Fixnum
Puede definir métodos y llamarlos:
1 >> def saludo
2 >> puts "Hola Mundo"
3 >> end
4 => nil
5 >> saludo
6 Hola Mundo
7 => nil
---- Clases base ----
Ya que "todo" son objetos de alguna clase, más vale que comencemos por aprender
las más fundamentales del lenguaje, Fixnum, Bignum, Float, String, Array y Hash.
Números... Fixnum, Bignum, Float
Enteros, dejemos que nuestro código Ruby hable.
1 >> num = 8
2 => 8
3 >> 7.times do
4 ?> print num.class, " ", num, "\n"
5 >> num *= num
6 >> end
7 Fixnum 8
8 Fixnum 64
9 Fixnum 4096
10 Fixnum 16777216
11 Bignum 281474976710656
12 Bignum 79228162514264337593543950336
13 Bignum 6277101735386680763835789423207666416102355444464034512896
14 => 7
15 >> num = 3.14
16 => 3.14
17 >> 8.times do
18 ?> print num.class, " ", num, "\n"
19 >> num *= num
20 >> end
21 Float 3.14
22 Float 9.8596
23 Float 97.21171216
24 Float 9450.11698107869
25 Float 89304710.9560719
26 Float 7.97533139894754e+15
27 Float 6.36059109230385e+31
28 Float 4.04571190434951e+63
---- Cadenas de caracteres, String ----
1 >> "Hola Mundo".class
2 => String
3 >> "987".class
4 => String
<
---- Arreglos, Array ----
1 >> arreglo = ["a",1,"b",2]
2 => ["a", 1, "b", 2]
3 >> arreglo.class
4 => Array
5 >> arreglo[0]
6 => "a"
7 >> arreglo[1]
8 => 1
<
---- Arreglos indexados arbitrariamente, Hash ----
1 >> hash = { "color" => "rojo", "temperatura" => 75, 1 => "hoy"}
2 => {1=>"hoy", "temperatura"=>75, "color"=>"rojo"}
3 >> hash.class
4 => Hash
5 >> hash["color"]
6 => "rojo"
7 >> hash["temperatura"]
8 => 75
9 >> hash[1]
10 => "hoy"
---- Recapitulación rápida, los objetos y sus métodos, ¿documentación? ----
Teniendo cualquier objeto de cualquier clase a la mano, para acceder a su
métodos podemos usar la sintaxis objeto.método. En el ejemplo abajo llamamos al
popular método to_s que nos ofrece una representación en String del objeto en
cuestión.
1 >> hash.to_s
2 => "1hoytemperatura75colorrojo"
3 >> arreglo.to_s
4 => "a1b2"
5 >> 8.to_s
6 => "8"
Ahora bien, ¿dónde consigo la documentación de dichas clases y métodos? Demos
la bienvenida a ri para ayuda local en línea de comandos, y por supuesto, en la
web a http://www.ruby-doc.org/ . Francamente, en nuestros días la primera
fuente de información es la Web, y en segundo lugar, nuestros recursos locales
como ri. Entonces, y para efectos de esta serie de artículos, vamos a usar
inicialmente Ruby 1.8.7.
* http://www.ruby-doc.org/core-1.8.7/
* http://www.ruby-doc.org/stdlib-1.8.7/
Ejemplo de salida ri (extracto).
$ ri Fixnum
------------------------------------------------ Class: Fixnum < Integer
A +Fixnum+ holds +Integer+ values that can be represented in a
native machine word (minus 1 bit). If any operation on a +Fixnum+
exceeds this range, the value is automatically converted to a
+Bignum+.
...
Instance methods:
-----------------
%, &, *, **, +, -, -@, /, <, <<, <=, <=>, ==, >, >=, >>, [], ^,
__serialize__, abs, dclone, div, divmod, html_safe?, id2name,
modulo, power!, quo, rdiv, rpower, size, to_f, to_s, to_sym, xchr,
zero?, |, ~
---- Ruby es dinámico ¿ 2 + 2 = 4 ? ----
Uno de los aspectos notables de Ruby es su dinamismo, una forma de visualizarlo
es hacer uso del hecho que todas las clases están "abiertas" y es posible
redefinir sus métodos, por ejemplo:
----- fixnum_mod.rb -----
#!/usr/bin/ruby
#
class Fixnum
def +(otro)
100
end
end
puts (2+2).to_s
----- Y ahora ejecutamos nuestro programa: -----
$ ruby fixnum_mod.rb
100
Horror, hemos echado a perder el método sumar de Fixnum, por ello algunos
consideran peligroso los lenguajes dinámicos, sin embargo existe la forma de
protegernos de este tipo de modificaciones en el caso de que ello no sea
deseable. El ejemplo sin embargo demuestra que toda clase puede redefinir
cualquiera de sus métodos en tiempo de ejecución, en cualquier momento, este
dinamismo le da gran poder a Ruby, piense en una clase u objeto que evoluciona
y gana funcionalidad en el tiempo de existencia del programa, o que la pierde,
su funcionalidad puede mutar, cambiar. No puede devolver el cambio, no sin que
le enseñe cómo preservar el código sobrescrito, probablemente en la próxima
edición de esta columna.
---- Estructuras de control ----
Por supuesto que ningún lenguaje está completo si no tiene la capacidad de
ejecución de código condicionada, es decir, evaluar alguna condición o estado,
y proceder en consecuencia de distintas maneras. Abajo le resumimos las
estructuras más comunes.
1 # Evaluacion máxima 20
2 if evaluacion < 10
3 puts "Usted reprobó la asignatura."
4 elsif evaluacion > 16
5 puts "Usted obtuvo un grado sobresaliente."
6 else
7 puts "Usted aprobó la materia."
8 end
1 unless unaCancion.duracion > 180 then
2 costo = .25
3 else
4 costo = .35
5 end
1 case forma
2 when Cuadrado, Rectangulo
3 # ...
4 when Circulo
5 # ...
6 when Triangulo
7 # ...
8 else
9 # ...
10 end
---- Lazos e iteradores ----
Un iterador en Ruby es simplemente un método que puede invocar un bloque de
código. Note como se pasa la referencia del bloque de código y este a su vez
ejecutado por medio de la llamada yield.
Ruby Salida
1 def tres_veces Hola mundo
2 yield Hola mundo
3 yield Hola mundo
4 yield
5 end
6
7 tres_veces { puts "Hola Mundo" }
Algunos iteradores son muy comunes en muchas clases Ruby para representar
colecciones, por ejemplo each en un arreglo simple. Note que each además de
iterar por cada uno de los elementos del arreglo, pasa un argumento al bloque
de código ha ser ejecutado, en este caso pasa el contenido correspondiente en
el arreglo.
Ruby Salida
i| puts i } 1
3
5
7
9
Lazos con while y until.
Ruby Salida
1 peso = 5 10
2 while peso < 100 20
3 peso = peso * 2 40
4 puts peso 80
5 end 160
Ruby Salida
1 peso = 5 10
2 until peso > 100 20
3 peso = peso * 2 40
4 puts peso 80
5 end 160
---- Lazo con for y loop: ----
Ruby Salida
1 for i in 1..8 do 1
2 puts i 2
3 end 3
4
5
6
7
8
Ruby Salida
1 num = 0 En el lazo por 0 vez
2 loop do En el lazo por 2 vez
3 puts "En el lazo por #{num} vez" En el lazo por 2 vez
4 num += 1 En el lazo por 3 vez
5 break unless num < 5 En el lazo por 4 vez
6 end
De salida, por supuesto hay mucho más acerca de Ruby y su mundo, usted podrá
hacer desde pequeños guiones (scripts) hasta poderosas aplicaciones de
escritorio o su último desarrollo web, no se detenga aquí y espero que nos
leamos en la próxima entrega de esta publicación, envíeme sus comentarios a
<[email protected]>.
Nuestro trabajo es resolver problemas concretos, no alimentar al compilador con
cucharilla, nos gustan los lenguajes dinámicos que se adapten a nosotros sin
reglas rígidas que seguir.
Gomix_
- end FWN 265 -
---
Pascal Calarco, Fedora Ambassador, Indiana, USA
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