Ruby on Rails/Utskriftsversjon
Introduksjon
redigerVelkommen til Ruby on Rails-boken!
redigerRuby on Rails er et MVC-rammeverk tilrettelagt for utvikling av nett-programmer. Det benytter språkene Ruby og YAML. Denne boken tar for seg dette rammeverket, og beskriver dets metoder og bruk, fra nybegynner til profesjonell.
Den antar at leseren har en grunnleggende forståelse for programmering, og kjenner til grunnleggende HTML/CSS. Disse er basiskunnskaper for å lage nett-programmer, og det antas kompetanse innenfor disse områdene i så godt som alle rammeverk for nett-programmering.
Boken er lagd for å leses fra start til slutt. Man bør forstå det som står i kapittel 2 for å lese kapittel 3 osv.
Kodeeksempler
redigerKodeeksempler vil se slik ut:
"Dette er en test."
Noen eksepler vil også vises "i ett med teksten"
.
Dersom koden i kodeeksemplene returnerer en eller annen verdi når koden blir kjørt, vil det vises på denne måten:
5 + 2
=> 7
"Test test" + " og test."
=> "Test test og test."
Dersom man kopierer koden i eksemplet, vil den ikke nødvendigvis returnere noe. Men for eksemplenes skyld lar vi "=>" indikere hva som kunne ha blitt returnert.
Installasjon
redigerLinux
redigerDet er nok trygt å anta at en som bruker Linux kan litt av hvert om installering av programvare. Derfor vil retningslinjene for hvordan man skal få det til være ganske generelle. Referer til http://google.com og andre kilder for distribusjons-spesifikke retningslinjer.
Først må Ruby og RubyGems installeres. Disse kan enten kompileres på egen hånd eller installeres via pakkebehandlingssystemet (apt-get, dpkg etc). Husk at Readline må installeres før man kompilerer Ruby for at IRb og andre verktøy skal virke. Når RubyGems er installert, kjøres sudo gem install rails --include-dependencies
for å installere Rails.
Merk at det er vanlig at binaries man installerer med RubyGems legger seg i RubyGems sin egen bin
-mappe. Denne må legges i $PATH for at rails
-kommandoen skal virke på samme måte som denne boken bruker den.
Windows
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- Installer Ruby og Ruby Gems(med http://rubyforge.org/projects/rubyinstaller/)
- Bruk Ruby Gems til å installere Rails og alle dens "depenencies".
OS X
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NB: Neste versjon av OS X, 10.5, vil ha Ruby on Rails ferdiginstallert.
Kompileringsverktøy
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Man kan installere Rails ved hjelp av Fink, MacPorts eller ved å kompilere på egen hånd. Uansett hvilket alternativ som velges, trengs et kompileringsverktøy. Når man bruker Fink/MacPorts, gjør man (som oftest) teknisk sett det samme som å kompilere selv, bortsett fra at automatiseringsverktøyet tar seg av nedlasting av filer, installering av annen programvare det man installerer er avhengig av etc. Når man kompilerer selv, uten å bruke Fink/MacPorts, vil man også trenge et kompileringsverktøy.
Det enklest tilgjengelige kompileringsverktøyet for OS X er GCC, GNU Compiler Collection. GCC følger med Apples Xcode-pakke, som kan lastes ned fra http://developer.apple.com.
Etter å ha registrert seg (helt gratis), naviger til https://connect.apple.com/cgi-bin/WebObjects/MemberSite.woa/wa/getSoftware?bundleID=19681, logg inn, og last ned. Kjør Xcode-installasjonen, og installer. Det er ikke nødvendig å installere hele Xcode-pakken, det holder å installere Xcode-hoveddelen og GCC.
Man kan også installere GCC via MacPorts.
Kompilere selv
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(Takk til http://hivelogic.com/narrative/articles/ruby-rails-mongrel-mysql-osx)
Legg til følgende i filen ~/.bash_login:
export PATH="/usr/local/bin:/usr/local/sbin:/usr/local/mysql/bin:$PATH"
Last ned nyeste versjon av w:Readline fra ftp://ftp.gnu.org/gnu/readline/:
wget ftp://ftp.gnu.org/gnu/readline/readline-XX.tar.gz
Pakk ut og kompiler:
tar xzvf readline-XX.tar.gz
cd readline-XX
./configure --prefix=/usr/local
make
sudo make install
Passordet sudo
spør om er det samme passordet som er knyttet til brukerkontoen i OS X. Med andre ord, det man bruker til å logge inn, installere programvare etc.
Last ned nyeste versjon av Ruby fra http://ruby-lang.org (bruk URL-en fra ruby-lang.org, ikke den i eksemplet nedenfor).
wget ftp://ftp.ruby-lang.org/pub/ruby/XX/ruby-XX.tar.gz
Pakk ut og kompiler:
tar xzvf ruby-XX.tar.gz
cd ruby-XX
./configure --prefix=/usr/local --enable-pthread --with-readline-dir=/usr/local --enable-shared
make
sudo make install
Last ned og kompiler RubyGems fra http://rubyforge.org/projects/rubygems/
wget http://rubyforge.org/frs/download.php/20989/rubygems-XX.tgz
tar xzvf rubygems-XX.tar.gz
cd rubygems-XX.tar.gz
sudo sudo /usr/local/bin/ruby setup.rb
Dermed kan man bruke RubyGems til å installere Ruby on Rails.
sudo gem install rails --include-dependencies
Fink
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...
MacPorts
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...
Grunnleggende Ruby
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Objekter
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Så godt som alt i Ruby er et objekt. Mange har forsøkt å forklare hva et objekt er, men de aller fleste ender opp med å bli innlagt på et mentalsykehus. Kort sagt: poenget med objekter er å modellere virkeligheten. Dersom et objekt har en lengde, ligger informasjonen om lengden i selve objektet. Man trenger ikke en ekstern funksjon for å vite hvor langt det er. (Dette trenger sårt en bedre forklaring.)
Alle objekter har en klasse, og klassen definerer hva slags objekt det er.
5.class
=> Integer #(En Integer er et tall uten desimaler)
"Dette er en tekst".class
=> String #(en String er en samling tekst, symboler tall etc.
["Fiolin", "Gitar", "Tuba"].class
=> Array #(et Array er en samling av objekter)
#Og alt etter '#' blir ansett som en kommentar, og vil ikke bli
#lest som Ruby-kode.
Alle «tingene» (som 5
, Dette er en tekst
etc) har en klasse. Eksempler på klasser er Integer
(tall uten desimaler) og String
(tekstsbiter med tall, symboler etc). Klassen til objektet definerer hva slags type objekt det er, og hva du kan gjøre med det.
Med ett Integer
-objekt kan man gjøre typiske numeriske kalkulasjoner.
1 + 2
=> 3
6 - 1
=> 5
8 / 2
=> 4
Ett String
-objekt oppfører seg annerledes, siden det er av en annen klasse.
"Hei på deg".upcase
=> "HEI PÅ DEG"
"Snakke baklengs".reverse
=>"sgnelkab ekkanS"
"Legg meg" + " til deg."
=> "Legg meg til deg."
"5" + "2"
=> "52"
Metoder
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Metoder er beskjeder man sender til objekter.
Det finnes to ulike typer metoder. Klassemetoder og instansmetoder. Klassemetoder kaller man direkte på en klasse, som String
, mens instansemetoder kalles på en instans av noe. new
er en klassemetode av String
, mens upcase
er en instansmetode av String
.
Logikken er at klassemetoder gir funksjonalitet som går direkte på klassen.
Lag klasser
rediger
Klassene String
og Integer
er innebygd i Ruby. I Ruby kan man også lage nye klasser, og gi dem egenskaper.
class Vehicle
def move_forward
"moving forward"
end
def stop
"stopped"
end
end
def
er et nøkkelord (end
og class
er også nøkkelord) for å definere en metode. Det som står etter def
er navnet på metoden, i dette tilfellet move_forward
og stop
.
Slik virker den nye klassen:
#Lag en instans av Vehicle
vehicle = Vehicle.new
vehicle.class
=> Vehicle
vehicle.move_forward
=> "moving forward"
Arving av egenskaper
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En klasse kan være en underklasse av en annen klasse. En underklasse vil arve alle egenskapene til klassen den er underklasse av.
class Bicycle < Vehicle
def ring_bell
"pling plong"
end
def pedal
"pedaling"
end
end
Det kan brukes på denne måten.
bicycle = Bicycle.new
bicycle.ring_bell
=> "pling plong"
# arver metoder fra over-klassen
bicycle.stop
=> "stopped"
bicycle.tullball
=> NoMethodError: "undefined method ‘tullball’ for Vehicle"
Metoden stop
ble ikke definert i klassen Bicycle
. Den metoden arvet Bicycle
fra Vehicle
.
Ruby har et helt sett med innebygde klasser. Kernel
ligger på topp, og definerer nøkkelordene som def
, return
, class
. Kernel
sin underklasse Object
definerer metoder som ettellerannet.class
, og andre liknende «globale» metoder, som ettellerannent.object_id
, ettellerannet.send
, ettelerannet.inspect
osv.
I stedet for å skrive ettellerannet.metode
for å referere til en instansmetode, er det vanlig å bruke Klasse#metode
. Så, dersom den forestilte klassen Queue
har instansemetoden move_forward
og klassemetoden find_all
, kan man referere til dette som Queue#move_forward
og Queue.find_all
. Dette kan ikke brukes på denne måten i selve språket, da #
definerer en kommentar i koden. Det man ville skrevet som Queue#move_forward
vil i virkeligheten bli skrevet slik:
queue_item = Queue.new
queue_item.move_forward
Lagring av data
rediger
Et objekt kan settes opp slik at det inneholder data.
class Vehicle
def initialize(brand, horse_power)
@brand = brand
@horse_power = horse_power
end
def brand
@brand
end
def horse_power
@horse_power
end
end
initialize
-metoden har Vehicle
arvet fra Object
-klassen. Den brukes til å definere hva som skal skje når man lager en ny instans av klassen man definerer den i.
Variabler som @ser_ut_som_dette
er instansvariabler. De er tilgjengelige i den instansen av klassen de er satt i.
not_working = Vehicle.new
=> ArgumentError: "wrong number of arguments (0 for 2)"
my_car = Vehicle.new("Volvo", 192)
my_car.horse_power
=> 192
Logisk nok deles ikke verdiene på tvers av instanser.
v1 = Vehicle.new("Subaru", 110)
v2 = Vehicle.new("Fiat", 97)
v1.horse_power
=> 110
v2.horse_power
=> 97
Det finnes også funksjonalitet for å redigere data etter instansen er laget.
class Vehicle
def initialize(brand, horse_power)
@brand = brand
@horse_power = horse_power
end
def brand
@brand
end
def horse_power
@horse_power
end
def set_brand(brand)
@brand = brand
end
def set_horse_power(horse_power)
@horse_power = horse_power
end
end
Dette kan brukes på følgende måte:
my_bmw = Vehicle.new("BMW", 182)
my_bmw.horse_power
=> 182
my_bmw.set_horse_power(212)
my_bmw.horse_power
=> 212
I de aller fleste tilfeller ønsker man å gjøre my_bmw.horse_power = 138
. For å sette opp dette, definer metonede på følgende måte:
class Vehicle
def horse_power=(horse_power)
@horse_power = horse_power
end
end
my_saab = Vehicle.new("saab", 177)
my_saab.horse_power = 172
my_saab.horse_power
=> 172
Siden det er ganske tungvint å skrive alle disse metodene - særlig hvis man har mange attributter - finnes det snarveier for å sette opp en klasse på denne måten med attr_reader
, attr_writer
og attr_accessor
.
class Vehicle
# definerer Vehicle#brand og Vehicle#horse_power
attr_reader :brand, :horse_power
# definerer Vehicle#max_speed=
attr_writer :max_speed
# defivener Vehicle#weight og Vehicle#weight=
attr_accessor :weight
def initialize(brand, horse_power)
@brand = brand
@horse_power = horse_power
end
# Siden @max_speed bare er satt med attr_writer, defineres
# denne metoden for å vise verdien av @max_speed
def max_speed
@max_speed
end
end
a_truck = Vehicle.new("Scania", 496)
a_truck.horse_power
=> 496
a_truck.max_speed
=> nil
a_truck.max_speed = 120
a_truck.max_speed
=> 120
a_truck.weight = 8000
a_truck.weight
=> 8000
Grunnleggende Rails
rediger
Rammeverket Ruby on Rails
rediger
Om de ulike mappene/filene som genereres med rails
-kommandoen.
Rails er Ruby
rediger
Om hvordan ActiveRecord::Base brukes for å gi modellene egenskaper. Ulike klasse/instans-metoder for modeller. Det samme med kontrollere.
GNU Free Documentation License
rediger
GNU Free Documentation License
Version 1.3, 3 November 2008
Copyright (C) 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc.
https://fsf.org
Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed.
0. PREAMBLE
rediger
The purpose of this License is to make a manual, textbook, or other
functional and useful document "free" in the sense of freedom: to
assure everyone the effective freedom to copy and redistribute it,
with or without modifying it, either commercially or noncommercially.
Secondarily, this License preserves for the author and publisher a way
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for modifications made by others.
This License is a kind of "copyleft", which means that derivative
works of the document must themselves be free in the same sense. It
complements the GNU General Public License, which is a copyleft
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We have designed this License in order to use it for manuals for free
software, because free software needs free documentation: a free
program should come with manuals providing the same freedoms that the
software does. But this License is not limited to software manuals;
it can be used for any textual work, regardless of subject matter or
whether it is published as a printed book. We recommend this License
principally for works whose purpose is instruction or reference.
1. APPLICABILITY AND DEFINITIONS
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This License applies to any manual or other work, in any medium, that
contains a notice placed by the copyright holder saying it can be
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A "Modified Version" of the Document means any work containing the
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The "Invariant Sections" are certain Secondary Sections whose titles
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The Document may include Warranty Disclaimers next to the notice which
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no effect on the meaning of this License.
2. VERBATIM COPYING
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You may copy and distribute the Document in any medium, either
commercially or noncommercially, provided that this License, the
copyright notices, and the license notice saying this License applies
to the Document are reproduced in all copies, and that you add no
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You may also lend copies, under the same conditions stated above, and
you may publicly display copies.
3. COPYING IN QUANTITY
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If you publish printed copies (or copies in media that commonly have
printed covers) of the Document, numbering more than 100, and the
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Copying with changes limited to the covers, as long as they preserve
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as verbatim copying in other respects.
If the required texts for either cover are too voluminous to fit
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If you publish or distribute Opaque copies of the Document numbering
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It is requested, but not required, that you contact the authors of the
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4. MODIFICATIONS
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You may copy and distribute a Modified Version of the Document under
the conditions of sections 2 and 3 above, provided that you release
the Modified Version under precisely this License, with the Modified
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E. Add an appropriate copyright notice for your modifications
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I. Preserve the section Entitled "History", Preserve its Title, and add
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You may add a passage of up to five words as a Front-Cover Text, and a
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5. COMBINING DOCUMENTS
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You may combine the Document with other documents released under this
License, under the terms defined in section 4 above for modified
versions, provided that you include in the combination all of the
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Make the same adjustment to the section titles in the list of
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In the combination, you must combine any sections Entitled "History"
in the various original documents, forming one section Entitled
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and any sections Entitled "Dedications". You must delete all sections
Entitled "Endorsements".
6. COLLECTIONS OF DOCUMENTS
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You may make a collection consisting of the Document and other
documents released under this License, and replace the individual
copies of this License in the various documents with a single copy
that is included in the collection, provided that you follow the rules
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You may extract a single document from such a collection, and
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License in all other respects regarding verbatim copying of that
document.
7. AGGREGATION WITH INDEPENDENT WORKS
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A compilation of the Document or its derivatives with other separate
and independent documents or works, in or on a volume of a storage or
distribution medium, is called an "aggregate" if the copyright
resulting from the compilation is not used to limit the legal rights
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If the Cover Text requirement of section 3 is applicable to these
copies of the Document, then if the Document is less than one half of
the entire aggregate, the Document's Cover Texts may be placed on
covers that bracket the Document within the aggregate, or the
electronic equivalent of covers if the Document is in electronic form.
Otherwise they must appear on printed covers that bracket the whole
aggregate.
8. TRANSLATION
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Translation is considered a kind of modification, so you may
distribute translations of the Document under the terms of section 4.
Replacing Invariant Sections with translations requires special
permission from their copyright holders, but you may include
translations of some or all Invariant Sections in addition to the
original versions of these Invariant Sections. You may include a
translation of this License, and all the license notices in the
Document, and any Warranty Disclaimers, provided that you also include
the original English version of this License and the original versions
of those notices and disclaimers. In case of a disagreement between
the translation and the original version of this License or a notice
or disclaimer, the original version will prevail.
If a section in the Document is Entitled "Acknowledgements",
"Dedications", or "History", the requirement (section 4) to Preserve
its Title (section 1) will typically require changing the actual
title.
9. TERMINATION
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You may not copy, modify, sublicense, or distribute the Document
except as expressly provided under this License. Any attempt
otherwise to copy, modify, sublicense, or distribute it is void, and
will automatically terminate your rights under this License.
However, if you cease all violation of this License, then your license
from a particular copyright holder is reinstated (a) provisionally,
unless and until the copyright holder explicitly and finally
terminates your license, and (b) permanently, if the copyright holder
fails to notify you of the violation by some reasonable means prior to
60 days after the cessation.
Moreover, your license from a particular copyright holder is
reinstated permanently if the copyright holder notifies you of the
violation by some reasonable means, this is the first time you have
received notice of violation of this License (for any work) from that
copyright holder, and you cure the violation prior to 30 days after
your receipt of the notice.
Termination of your rights under this section does not terminate the
licenses of parties who have received copies or rights from you under
this License. If your rights have been terminated and not permanently
reinstated, receipt of a copy of some or all of the same material does
not give you any rights to use it.
10. FUTURE REVISIONS OF THIS LICENSE
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The Free Software Foundation may publish new, revised versions of the
GNU Free Documentation License from time to time. Such new versions
will be similar in spirit to the present version, but may differ in
detail to address new problems or concerns. See
https://www.gnu.org/licenses/.
Each version of the License is given a distinguishing version number.
If the Document specifies that a particular numbered version of this
License "or any later version" applies to it, you have the option of
following the terms and conditions either of that specified version or
of any later version that has been published (not as a draft) by the
Free Software Foundation. If the Document does not specify a version
number of this License, you may choose any version ever published (not
as a draft) by the Free Software Foundation. If the Document
specifies that a proxy can decide which future versions of this
License can be used, that proxy's public statement of acceptance of a
version permanently authorizes you to choose that version for the
Document.
11. RELICENSING
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"Massive Multiauthor Collaboration Site" (or "MMC Site") means any
World Wide Web server that publishes copyrightable works and also
provides prominent facilities for anybody to edit those works. A
public wiki that anybody can edit is an example of such a server. A
"Massive Multiauthor Collaboration" (or "MMC") contained in the site
means any set of copyrightable works thus published on the MMC site.
"CC-BY-SA" means the Creative Commons Attribution-Share Alike 3.0
license published by Creative Commons Corporation, a not-for-profit
corporation with a principal place of business in San Francisco,
California, as well as future copyleft versions of that license
published by that same organization.
"Incorporate" means to publish or republish a Document, in whole or in
part, as part of another Document.
An MMC is "eligible for relicensing" if it is licensed under this
License, and if all works that were first published under this License
somewhere other than this MMC, and subsequently incorporated in whole or
in part into the MMC, (1) had no cover texts or invariant sections, and
(2) were thus incorporated prior to November 1, 2008.
The operator of an MMC Site may republish an MMC contained in the site
under CC-BY-SA on the same site at any time before August 1, 2009,
provided the MMC is eligible for relicensing.
ADDENDUM: How to use this License for your documents
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To use this License in a document you have written, include a copy of
the License in the document and put the following copyright and
license notices just after the title page:
Copyright (c) YEAR YOUR NAME.
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3
or any later version published by the Free Software Foundation;
with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.
A copy of the license is included in the section entitled "GNU
Free Documentation License".
If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts,
replace the "with...Texts." line with this:
with the Invariant Sections being LIST THEIR TITLES, with the
Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST.
If you have Invariant Sections without Cover Texts, or some other
combination of the three, merge those two alternatives to suit the
situation.
If your document contains nontrivial examples of program code, we
recommend releasing these examples in parallel under your choice of
free software license, such as the GNU General Public License,
to permit their use in free software.