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  • Ruby SerialPorts Gem

    - by Seth Archer
    Using Ruby SerialPorts Gem to interact with hardware. When I write a byte array to the hardware using a program called "Serial Port Monitor" the hardware responds correctly. However, when I write the same byte array using ruby it doesn't work unless I do a read request just before the write request. This device doesn't respond correctly with this sp = SerialPort.new(args) sp.write [200.chr, 30.chr, 6.chr, 5.chr, 1.chr, 2.chr, 0.chr, 244.chr] But it does if I add a read request before the write. Like this sp SerialPort.new(args) sp.read sp.write [200.chr, 30.chr, 6.chr, 5.chr, 1.chr, 2.chr, 0.chr, 244.chr] This works, but I'm at a loss as to why. I should also add that the first snippet does work occasionally maybe 1/10 of the time.

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  • Spawn a background process in Ruby

    - by Dave DeLong
    I'm writing a ruby bootstrapping script for a school project, and part of this bootstrapping process is to start a couple of background processes (which are written and function properly). What I'd like to do is something along the lines of: `/path/to/daemon1 &` `/path/to/daemon2 &` `/path/to/daemon3 &` However, that blocks on the first call to execute daemon1. I've seen references to a Process.spawn method, but that seems to be a 1.9+ feature, and I'm limited to Ruby 1.8. I've also tried to execute these daemons from different threads, but I'd like my bootstrap script to be able to exit. So how can I start these background processes so that my bootstrap script doesn't block and can exit (but still have the daemons running in the background)? Thanks!

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  • ruby on rails named scope implementation

    - by Engwan
    From the book Agile Web Development With Rails class Order < ActiveRecord::Base named_scope :last_n_days, lambda { |days| {:conditions => ['updated < ?' , days] } } named_scope :checks, :conditions => {:pay_type => :check} end The statement orders = Orders.checks.last_n_days(7) will result to only one query to the database. How does rails implement this? I'm new to Ruby and I'm wondering if there's a special construct that allows this to happen. To be able to chain methods like that, the functions generated by named_scope must be returning themselves or an object than can be scoped further. But how does Ruby know that it is the last function call and that it should query the database now? I ask this because the statement above actually queries the database and not just returns an SQL statement that results from chaining.

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  • [Ruby] OpenSSL verify certificate from own CA

    - by sardaukar
    Hello all and thanks for your time reading this. I need to verify certificates issued by my own CA, for which I have a certificate. How can I do the equivalent to openssl's openssl verify -CAfile in Ruby code? The RDoc for OpenSSL is not very helpful in this regard. I've tried: require 'openssl' ca = OpenSSL::X509::Certificate.new(File.read('ca-cert.pem')) lic = OpenSSL::X509::Certificate.new(File.read('cert.pem')) puts lic.verify( ca ) but I get: test.rb:7:in `verify': wrong argument (OpenSSL::X509::Certificate)! (Expected kind of OpenSSL::PKey::PKey) (TypeError) from test.rb:7 I can't even find "verify" in the OpenSSL Rdoc at http://www.ruby-doc.org/stdlib/libdoc/openssl/rdoc/index.html. Any help is appreciated. Thanks again!

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  • Ruby on Rails website hosting

    - by sfactor
    i want to start a website. it'll be a small community based website. i've learned a fair bit of ruby on rails and am planning to use it. however, i have never deployed a production website before. i've just practiced in my local computer. i wanted to know what are the things i need to deploy the website on the internet. what is the best place to get a domain name and web hosting, esp for ruby on rails sites. how are cloud based services like amazon EC2 etc different from a traditional web host. which is a better choice. what else might i need to do to deploy a website. also i may happen to have a fair bit of users in the future. so how to go about planning for scalability issues. how to sites like twitter, fmylife.com etc all go about these things.

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  • Readline, the Input Record Separator and Ruby

    - by JustSmith
    In Ruby I'm looking to read data until I reach a delimiter or end of file. I found this is possible by redefining $/ or the $INPUT_RECORD_SEPARATOR to my delimiter. However with all the "features" in the Ruby language it seems hokey to change the value of a global to do this. Also, readline used to consume the delimiter while not it is included in what is returned. Is there any other way to "read until" while consuming the delimiter that doesn't involve getting the values char by char in a loop?

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  • IRb: how to start an interactive ruby session with pre-loaded classes

    - by Shyam
    Hi, As I am going through my journey by adopting the Ruby language, I spend a lot of time inside IRb. It's just fantastic! But, as I am not very aware of it's capabilities, and still a nuby with Ruby, I would like to know the following: How can I 'flush' the session, without restarting IRb (or is this not possible). How can I configure IRb to load a bunch of source files "hello.rb" and "hello_objects.rb", i.e. at startup? I am heavily working in these and it would be nice to know a short hand to load these classes, without manually typing 'load' for each again. Thank you for your answers, comments and feedback!

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  • Serving files inside of directories with ruby and mongrel

    - by AdamB
    I made a simple web server in Ruby using the Mongrel gem. It works great for files in a single directory, but I run into some path issues when inside a directory. Lets say we have 2 files in a directory named "dir1", "index.html" and "style.css". If we visit http://host/dir1/index.html, the file is found, but style.css isn't because it's trying to load "style.css" from http://host/style.css instead of inside the directory. index.html is trying to load style.css as if its in the same directory as itself. <link href="style.css" rel="stylesheet" type="text/css" /> I can get the file if I enter the full path of style.css: /dir1/style.css but it doesn't seem to remember it's already inside a directory and that no path before a filename should serve from the current directory. This is the ruby code im using to serve out files. require 'rubygems' require 'mongrel' server = Mongrel::HttpServer.new("0.0.0.0", "3000") server.register("/", Mongrel::DirHandler.new(".")) server.run.join

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  • Detect number of IDLE processors ruby

    - by Yannick Wurm
    Hello, I work on shared linux machines with between 4 and 24 cores. To make best use of them, I use the following code to detect the number of processors from my ruby scripts: return `cat /proc/cpuinfo | grep processor | wc -l`.to_i (perhaps there is a pure-ruby way of doing this?) But sometimes a colleague is using six or eight of the 24 cores. (as seen via top). How can I get an estimate of the number of currently unused processors that I can use without making anyone upset? Thanks!

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  • Ruby delete method (string manipulation)

    - by brianheys
    I'm new to Ruby, and have been working my way through Mr Neighborly's Humble Little Ruby Guide. There have been a few typos in the code examples along the way, but I've always managed to work out what's wrong and subsequently fix it - until now! This is really basic, but I can't get the following example to work on Mac OS X (Snow Leopard): gone = "Got gone fool!" puts "Original: " + gone gone.delete!("o", "r-v") puts "deleted: " + gone Output I'm expecting is: Original: Got gone fool! deleted: G gne fl! Output I actually get is: Original: Got gone fool! deleted: Got gone fool! The delete! method doesn't seem to have had any effect. Can anyone shed any light on what's going wrong here? :-\

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  • Designing Web Service Using Ruby on Rails - Mapping ActiveRecord Models

    - by michaeldelorenzo
    I've put together a RoR application and would now like to publish a RESTful web service for interacting with my application. I'm not sure where to go exactly, I don't want to simply expose my ActiveRecord models since there is some data on each model that isn't needed or shouldn't be exposed via an API like this. I also don't want to create a SOAP solution. My application is built using Rails 2.3.5 and I hope to move to Rails 3.0 soon after its released. I'm basically looking for a way to map my ActiveRecord models to "models" that would be exposed via the web service. Is ActiveResource the correct thing to use? What about ActionWebService?

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  • Writing an app with Perl and Ruby?

    - by Jeff Erickson
    I am working on a project that is mostly Ruby on Rails. However, I need to generate and parse Excel files in this project (I know, I know...), so I've been using Perl's Spreadsheet::WriteExcel and Spreadsheet::ParseExcel which work well. However, what is the best way to combine this use of Perl with the larger Ruby on Rails app? Is calling the Perl script with backticks the kosher way to go about this? It feels a little hacky to me, but if that is the only (or best) way, then that's what I'll do. I wanted to reach out and see if anyone else has some suggestions or advise. Thank you!

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  • Go Channels in Ruby

    - by Julius Eckert
    In the Go programming language, you can send Messages around using a construct called "Channels". http://golang.org/doc/effective_go.html#channels I would love to use something like that in Ruby, especially for IPC. Pseudocode of what I want: channel = Channel.new fork do 3.times{ channel.send("foo ") } exit! end Thread.new do 3.times{ channel.send("bar ") } end loop do print channel.recv end # ~> bar foo foo bar bar foo Is there any construct, library or equivalent for Ruby which works like that ? If not: What is the best way to build such an abstraction?

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  • Lazy evaluation in Ruby

    - by fifigyuri
    I have a situation for Ruby, where an object is possibly necessary to be created, but it is not sure. And as the creation of the object might be costly I am not too eager creating it. I think this is a clear case for lazy loading. How can I define an object which is not created only when someone sends a message to it? The object would be created in a block. Is there a way for simple lazy loading/initialisation in Ruby? Are these things supported by some gems, which provide different solutions for various cases of lazy initialisation of objects? Thanks for your suggestions!

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  • Ruby and Forking

    - by Cory
    Quick question about Ruby forking - I ran across a bit of forking code in Resque earlier that was sexy as hell but tripped me up for a few. I'm hoping for someone to give me a little more detail about what's going on here. Specifically - it would appear that forking spawns a child (expected) and kicks it straight into the 'else' side of my condition (less expected. Is that expected behavior? A Ruby idiom? My IRB hack here: def fork return true if @cant_fork begin if Kernel.respond_to?(:fork) Kernel.fork else raise NotImplementedError end rescue NotImplementedError @cant_fork = true nil end end def do_something puts "Starting do_something" if foo = fork puts "we are forking from #{Process.pid}" Process.wait else puts "no need to fork, let's get to work: #{Process.pid} under #{Process.ppid}" puts "doing it" end end do_something

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  • Needing forward declaration in Ruby

    - by dbarbosa
    Hi, I am trying to write a Ruby script in one file. I would like to know if it is possible to write the "main" function in the beginning, having the other functions that are used by main, defined after it. In other words, I would like to call a not yet defined function, so that they do not depends on definition order. Just changing the order is not possible because it gives an "undefined method" error. In C/C++ we use forward declarations... is there something similar in Ruby or another solution to this?

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  • Is it possible to call Javascript's onsubmit event programatically on a form?

    - by hoyhoy
    In Ruby on Rails, I'm attempting to update the innerHTML of a div tag using the form_remote_tag helper. This update happens whenever an associated select tag receives an onchange event. The problem is, <select onchange="this.form.submit();">; doesn't work. Nor does document.forms[0].submit(). The only way to get the onsubmit code generated in the form_remote_tag to execute is to create a hidden submit button, and invoke the click method on the button from the select tag. Here's a working ERb partial example. <% form_remote_tag :url => product_path, :update => 'content', :method => 'get' do -%> <% content_tag :div, :id => 'content' do -%> <%= select_tag :update, options_for_select([["foo", 1], ["bar", 2]]), :onchange => "this.form.commit.click" %> <%= submit_tag 'submit_button', :style => "display: none" %> <% end %> <% end %> What I want to do is something like this, but it doesn't work. <% form_remote_tag :url => product_path, :update => 'content', :method => 'get' do -%> <% content_tag :div, :id => 'content' do -%> # the following line does not work <%= select_tag :update, options_for_select([["foo", 1], ["bar", 2]]), :onchange => "this.form.onsubmit()" %> <% end %> <% end %> So, is there any way to remove the invisible submit button for this use case? There seems to be some confusion. So, let me explain. The basic problem is that submit() doesn't call the onsubmit() code rendered into the form. The actual HTML form that Rails renders from this ERb looks like this: <form action="/products/1" method="post" onsubmit="new Ajax.Updater('content', '/products/1', {asynchronous:true, evalScripts:true, method:'get', parameters:Form.serialize(this)}); return false;"> <div style="margin:0;padding:0"> <input name="authenticity_token" type="hidden" value="4eacf78eb87e9262a0b631a8a6e417e9a5957cab" /> </div> <div id="content"> <select id="update" name="update" onchange="this.form.commit.click"> <option value="1">foo</option> <option value="2">bar</option> </select> <input name="commit" style="display: none" type="submit" value="submit_button" /> </div> </form> I want to axe the invisible submit button, but using a straight form.submit appears to not work. So, I need some way to call the form's onsubmit event code. Update: Orion Edwards solution would work if there wasn't a return(false); generated by Rails. I'm not sure which is worse though, sending a phantom click to an invisible submit button or calling eval on the getAttribute('onsubmit') call after removing the return call with a javascript string replacement!

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  • Ruby Multithreading: making one thread wait for a signal from another

    - by Peter
    In Ruby, I want to have two threads running at the same time, and want the background thread to periodically signal the foreground thread. How do I get the foreground thread to block until the background thread says 'go'? I can think of a few ways to do it, but am after the most appropriate, idiomatic Ruby method. In code: loop do # background, thread 1 sleep 3 receive_input # tell foreground input is ready # <-- how do I do this? end and loop do # foreground, thread 2 wait_for_signal_from_background # <-- how do I do this? do_something end

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