Mon manuscrit de thèse sera rédigé en LaTeX (le premier qui me parle de Word se fera frapper avec violence 
) et histoire d’automatiser les choses, j’ai écrit un script de compilation en Ruby.
J’aurai pu utiliser un Makefile, un des scripts existants (il y en a un très bien en Perl dont j’ai oublié le nom), du Python, du Groovy… mais ce script là me va très bien !
#!/usr/bin/env ruby
require 'optparse'
require 'fileutils'
MAIN_FILE = "phd-thesis"
PDFLATEX = "pdflatex #{MAIN_FILE}.tex"
BIBTEX = "bibtex #{MAIN_FILE}.aux"
def build_pdf
return unless system PDFLATEX
return unless system BIBTEX
callcc do |stop_build|
3.times do
status = system PDFLATEX
stop_build.call unless status
end
end
end
def single_compilation
system PDFLATEX
end
def clean_artifacts
extensions = %w[blg log pdf aux bbl lof lot out toc tps]
files = extensions.map { |ext| "#{MAIN_FILE}.#{ext}" }
FileUtils::Verbose::rm files, { :force => true }
end
def open_pdf(how)
system "#{how} #{MAIN_FILE}.pdf"
end
def run
options = {
:command => :pdf
}
OptionParser.new do |opts|
opts.banner = "Usage: build.rb [options]"
opts.on("--pdf", "Build the PDF output (default)") do |pdf|
options[:command] = :pdf
end
opts.on("--oneshot", "Single LaTeX compilation") do |oneshot|
options[:command] = :oneshot
end
opts.on("--clean", "Clean the build artifacts") do |clean|
options[:command] = :clean
end
opts.on("--open-pdf [HOW]", "Open the generated PDF with HOW)") do |how|
options[:openpdf] = how
end
opts.on_tail("-h", "--help", "Show this message") do
puts opts
exit
end
end.parse!
case options[:command]
when :pdf
build_pdf
open_pdf(options[:openpdf]) if options[:openpdf]
when :oneshot
single_compilation
open_pdf(options[:openpdf]) if options[:openpdf]
when :clean
clean_artifacts
end
end
runJe ne garanti pas que le code soit parfait, alors n’hésitez pas à émettre des critiques constructives !
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I am giving a Ruby lecture tomorrow (some students happen to be quite lucky in fact). I wanted to present an example of a Ruby On Rails style meta programming technique. For example you can have a find_by_name or find_by_email method on your ActiveRecord objects. Those methods are in fact generated on the fly using a technique which looks like what follows. This has probably been explained a million times somewhere else on the web, but I don’t care
So let’s start with a very basic contacts book class which looks like:
class ContactBook
def initialize
@contacts = Hash.new
end
def add_contact(name, email)
@contacts[name] = email
end
def contact_named(name)
@contacts[name]
end
end
book = ContactBook.new
book.add_contact "Pierre", "pierre@zzland.fr"
book.add_contact "Julien", "julien@zzland.fr"
book.add_contact "Yoan", "yoan@zzland.fr"
book.add_contact "Mr Bean", "info@mrbean.com"Nothing impressive here, so now let’s get all the contacts whose email contain a given substring:
class ContactBook
def email_containing(str)
@contacts.select { |key, value| value.include? str }
end
end
def display_contact(contact)
puts "#{contact[0]} <#{contact[1]}>"
end
zzland = book.email_containing "zzland"
zzland.each { |contact| display_contact(contact) }But what if we could have email_thestringtolookfor methods instead of this? Let’s do it by evaluating some code on the fly:
class ContactBook
def method_missing(id, *args)
method_name = id.to_s
if method_name[0..5] == 'email_'
str = method_name[6..method_name.length]
to_eval = <<-END_FUNC
def email_#{str}
@contacts.select { |key, value| value.include? "#{str}" }
end
END_FUNC
instance_eval to_eval
return eval("self.email_#{str}")
end
end
end
zzland = book.email_zzland
bean = book.email_bean
zzland.each { |contact| display_contact(contact) }
puts "-----"
bean.each { |contact| display_contact(contact) }
method_missing is invoked whenever a message is sent to the class instance, but no matching method name can be found.- If the name starts with
email_, then we are in luck! (note that I should throw an exception if the name doesn’t start with this to comply with the Ruby semantics, but I was too lazy for that)
- We generate a new method for the instance through evaluation.
- We do not forget to invoke the new method through evaluation, as the original call would return
nil since the method had not been found.
Nice isn’t it? 
2 Comments »
Today I had fun playing with Rinda, the Ruby implementation of the Linda distributed process coordination paradigm. I also had some time for blogging, something that I haven’t done for a few days because of too much work (and there still a bunch left to be done )
I won’t go through the theory behind Linda, but the gross idea is to use a shared memory space that implements the distributed blackboard paradigm : the Tuple Space. It can be summarized on the following figure:
Data is represented as sets of tuples which often have a limited lifetime. The tuple space provides the distributed processes the following primitives:
- write: writes a tuple to the tuple space
- read: reads a tuple from the tuple space
- take: reads and removes a tuple from the tuple space
The beauty of the model lies in the fact that the tuple space guarantees atomic operations and periodically cleans up old tuples. Also, reading operations match a tuple on:
- the length of the requested and available tuples
- the matching (exact value, regular expressions, …) of certain elements of the tuple.
I have put together a first Ruby program that reads text from the console, and writes tuples whenever a line is entered. The other program takes every new tuple that is emitted.
emitter.rb
#!/usr/bin/env ruby
require 'drb/drb'
require 'rinda/ring'
require 'rinda/tuplespace'
DRb.start_service
tuple_space = Rinda::TupleSpace.new
ring_server = Rinda::RingServer.new tuple_space
while true
tuple_space.write [:message, gets]
end
receiver.rb
#!/usr/bin/env ruby
require 'drb/drb'
require 'rinda/ring'
require 'rinda/tuplespace'
DRb.start_service
tuple_space = Rinda::RingFinger.primary
while true
puts tuple_space.take([:message, nil])[1]
end
What I really like is the simplicity of the code, thanks to the cleanness of Linda and the elegance of Ruby The other thing is that DRb is such a straightforward way to use distributed objects in Ruby…
BTW there is a Java implementation of this paradigm called JavaSpaces.
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