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  • Send string from java (or other platform) to application

    - by MrSnowflake
    I want to send a barcode, read with my cellphone, to my computer. My computer has a simple server running, which listens to barcodes. When a barcode arrives, the server app should be able to input the value of the received barcode into the active application (I don't really care which application is going to get the input, the user should be able to select gedit, a terminal window or the browser if they choose to). My language at the moment is Java on GNU/Linux (Ubuntu), so I know about the Robot class. But the Robot class emulates a keyboard, which means: when you send VK_1 on a US keyboard layout, the output is '1' indeed, but when you send VK_1 on another layout (like belgian, which I use), which requires shift for the '1' key, the output is '&' (this is the character on the '1' key, when you don't hold shift). I also found xsendkeys, but this application too requires you to specify whether you need to hold shift. So it will be able to send an 'a' but for an 'A' (thus capital) you need to specify you want to hold shift with your 'a'. Isn't there an easy way to do this, for GNU/Linux and Windows, just using strings. I want to be able to send "12a68dd" to the active application. And I also would like to be able to send UTF-8 characters to the active application. I have been looking for a solution, but most require the breakdown in multiple keystrokes, which are often dependent on the keyboard layout.

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  • Stable/repeatable random sort (MySQL, Rails)

    - by Matt Rogish
    I'd like to paginate through a randomly sorted list of ActiveRecord models (rows from MySQL database). However, this randomization needs to persist on a per-session basis, so that other people that visit the website also receive a random, paginate-able list of records. Let's say there are enough entities (tens of thousands) that storing the randomly sorted ID values in either the session or a cookie is too large, so I must temporarily persist it in some other way (MySQL, file, etc.). Initially I thought I could create a function based on the session ID and the page ID (returning the object IDs for that page) however since the object ID values in MySQL are not sequential (there are gaps), that seemed to fall apart as I was poking at it. The nice thing is that it would require no/minimal storage but the downsides are that it is likely pretty complex to implement and probably CPU intensive. My feeling is I should create an intersection table, something like: random_sorts( sort_id, created_at, user_id NULL if guest) random_sort_items( sort_id, item_id, position ) And then simply store the 'sort_id' in the session. Then, I can paginate the random_sorts WHERE sort_id = n ORDER BY position LIMIT... as usual. Of course, I'd have to put some sort of a reaper in there to remove them after some period of inactivity (based on random_sorts.created_at). Unfortunately, I'd have to invalidate the sort as new objects were created (and/or old objects being removed, although deletion is very rare). And, as load increases the size/performance of this table (even properly indexed) drops. It seems like this ought to be a solved problem but I can't find any rails plugins that do this... Any ideas? Thanks!!

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  • In the meantime, to be or not to be ... productive!

    - by Jan Kuboschek
    I just moved back to Europe from the US after living there for 7 years. Apart from major adjustment issues, I'm currently looking for a job over here. I'm mainly interested in (IT) Consulting and, since these jobs typically require programming knowledge, such as Java, I'm trying to think of something productive to write (perhaps to demo my skills) while I'm waiting for my interviews (starting in two weeks. Folks here are a bit slower than in the US apparently...). I graduated from college about a year and a half ago and have a 4 year degree in international management/economics and about 3/4 of a 2 year degree in computer science finished. I've written my fair share of web software over the years, but nothing concrete that I could show, especially not in Java. Now, I've never had the problem of not having any idea what to write. Basic games I could write, but I'm not sure how well that'll come over when I walk into my interview and say "hey, I was bored. Take a look at my multiplayer space invaders game! Wanna try beating me??". Any thoughts? I browsed SourceForge the other day to find a nice little project to contribute to, but decided that I don't want to commit to someone else's project at this time. Any ideas, perhaps from someone who has been, or currently is, in a similar position would be much appreciated. Oh, and lastly: Instead of developing a program or two to demonstrate my skills, I could spend my time brushing up on UML and Perl. Any suggestions regarding that? Writing a demo vs. learning something new?

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  • Best "Loading" feedback for ASP.Net?

    - by IP
    So, we have an ASP.Net application - fairly standard - and in there are lots of updatepanels, and postbacks. On some pages we have <ajax:UpdatePanelAnimationExtender ID="ae" runat="server" TargetControlID="updatePanel" BehaviorID="UpdateAnimation"> <Animations> <OnUpdating> <FadeOut Duration="0.1" minimumOpacity=".3" /> </OnUpdating> <OnUpdated> <FadeIn minimumOpacity=".5" Duration="0" /> </OnUpdated> </Animations> </ajax:UpdatePanelAnimationExtender> Which basically whites out the page when a postback is going on (but this clashes with modal dialog grey backgrounds). In some cases we have a progressupdate control which just has a spinny icon in the middle of the page. But none of them seem particularly nice and all a bit clunky. They also require a lot of code in various places around the app. What methods do other people use and find effective?

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  • Accessing vars from another clojure namespace?

    - by erikcw
    In my main namespace, I have a top level var named "settings" which is initialized as an empty {}. My -main fn sets the contents of settings using def and conj based on some command line args (different database hosts for production/development, etc). I'm trying to access the contents of this map from another namespace to pull out some of the settings. When I try to compile with lein into an uberjar, I get a traceback saying "No such var: lb/settings". What am I missing? Is there a more idiomatic way to handle app wide settings such as these? Is it safe to use "def" inside of -main like I am, or should I be use an atom or ref to make this threadsafe? Thanks! (ns main (:use ...) (:gen-class)) (def settings {}) (defn -main [& args] (with-command-line-args... ;set devel? based on args (if (true? devel?) (def settings (conj settings {:mongodb {:host "127.0.0.1"} :memcached {:host "127.0.0.1"}})) (def settings (conj settings {:mongodb {:host "PRODUCTION_IP"} :memcached {:host "PRODUCTION_IP"}}))) ;file2.clj (ns some-other-namespace (:require [main :as lb] ...) ;configure MongoDB (congo/mongo! :db "dbname" :host (:host (mongodb lb/settings)))) ...

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  • Why doesn't this short php script send email?

    - by RoryG
    I can't seem to get my php script to send email. <?php echo "Does this page work?"; mail('my email address', 'test subject', 'test message'); ?> First, I have set the mail function settings in the php.ini file as follows: I checked my email account settings on outlook. It does not require authentication, its port is 25, and its type of encrypted connection is 'Auto'. Given this I configured my php.ini file accordingly: SMTP = ssl://smtp1.iis.com smtp_port = 25 Then I set: sendmail_from: my email address The echo statement prints out in the browser, so I know the php file is recognized and processed. But the browser also shows the following error: Warning: mail() [function.mail]: "sendmail_from" not set in php.ini or custom "From:" header missing in C:\xampp\htdocs\mailtest.php on line 3 I have clearly set the sendmail_from so I don't know what else to do. I have also tried removing the 'ssl://' part from the SMTP setting in the php.ini file, and configuring the php5.ini file. Which of these .ini files should I be configuring anyways?

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  • Working with PHP and MySQL - need a good and secure design with OO design

    - by Andrew
    I am new to PHP- first time developer. I am working on my web application and it is nearly done; nevertheless, most of my sql was done directly via code using direct mysql requests. This is the way I approached it: In classes_db.php I declared the db settings and created methods that I use to open and close DB connections. I declare those objects on my regular pages: class classes_db { public $dbserver = 'server; public $dbusername = 'user'; public $dbpassword = 'pass'; public $dbname = 'db'; function openDb() { $dbhandle = mysql_connect($this->dbserver, $this->dbusername, $this->dbpassword); if (!$dbhandle) { die('Could not connect: ' . mysql_error()); } $selected = mysql_select_db($this->dbname, $dbhandle) or die("Could not select the database"); return $dbhandle; } function closeDb($con) { mysql_close($con); } } On my regular page, I do this: <?php require 'classes_db.php'; session_start(); //create instance of the DB class $db = new classes_db(); //get dbhandle $dbhandle = $db->openDb(); //process query $result = mysql_query("update user set username = '" . $usernameFromForm . "' where iduser= " . $_SESSION['user']->iduser); //close the connection if (isset($dbhandle)) { $db->closeDb($dbhandle); } ?> My questions is: how to do it right and make it OO and secure? I know that I need incorporate prepared queries- how to do it the best way? Please provide some code

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  • How to combine two separate unrelated Git repositories into one with single history timeline

    - by Antony
    I have two unrelated (not sharing any ancestor check in) Git repositories, one is a super repository which consists a number of smaller projects (Lets call it repository A). Another one is just a makeshift local Git repository for a smaller project (lets call it repository B). Graphically, it would look like this A0-B0-C0-D0-E0-F0-G0-HEAD (repo A) A0-B0-C0-D0-E0-F0-G0-HEAD (remote/master bare repo pulled & pushed from repo A) A1-B1-C1-D1-E1-HEAD (repo B) Ideally, I would really like to merge repo B into repo A with a single history timeline. So it would appear that I originally started project in repo A. Graphically, this would be the ideal end result A0-A1-B1-B0-D1-C0-D0-E0-F0-G0-E1-H(from repo B)-HEAD (new repo A) A0-A1-B1-B0-D1-C0-D0-E0-F0-G0-E1-H(from repo B)-HEAD (remote/master bare repo pulled & pushed from repo A) I have been doing some reading with submodules and subtree (Pro Git is a pretty good book by the way), but both of them seem to cater solution towards maintaining two separate branch with sub module being able to pull changes from upstream and subtree being slightly less headache. Both solution require additional and specialized git commands to handle check ins and sync between master and sub tree/module branch. Both solution also result in multiple time-lines (with --squash you even get 3 timelines with subtree). The closest solution from SO seems to talk about "graft", but is that really it? The goal is to have a single unified repository where I can pull/push check-ins, so that there are no more repo B, just repo A in the end.

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  • Scalably processing large amount of comlpicated database data in PHP, many times a day.

    - by Eph
    I'm soon to be working on a project that poses a problem for me. It's going to require, at regular intervals throughout the day, processing tens of thousands of records, potentially over a million. Processing is going to involve several (potentially complicated) formulas and the generation of several random factors, writing some new data to a separate table, and updating the original records with some results. This needs to occur for all records, ideally, every three hours. Each new user to the site will be adding between 50 and 500 records that need to be processed in such a fashion, so the number will not be steady. The code hasn't been written, yet, as I'm still in the design process, mostly because of this issue. I know I'm going to need to use cron jobs, but I'm concerned that processing records of this size may cause the site to freeze up, perform slowly, or just piss off my hosting company every three hours. I'd like to know if anyone has any experience or tips on similar subjects? I've never worked at this magnitude before, and for all I know, this will be trivial to the server and not pose much of an issue. As long as ALL records are processed before the next three hour period occurs, I don't care if they aren't processed simultaneously (though, ideally, all records belonging to a specific user should be processed in the same batch), so I've been wondering if I should process in batches every 5 minutes, 15 minutes, hour, whatever works, and how best to approach this (and make it scalable in a way that is fair to all users)?

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  • Help me refactor my World Cup Challenge Script

    - by kylemac
    I am setting up a World Cup Challenge between some friends, and decided to practice my Ruby and write a small script to automate the process. The Problem: 32 World Cup qualifiers split into 4 tiers by their Fifa ranking 8 entries Each entry is assigned 1 random team per tier Winner takes all :-) I wrote something that suffices yet is admittedly brute force. But, in my attempt to improve my Ruby, I acknowlege that this code isn't the most elegant solution around - So I turn to you, the experts, to show me the way. It may be more clear to check out this gist - https://gist.github.com/91e1f1c392bed8074531 My Current (poor) solution: require 'yaml' @teams = YAML::load(File.open('teams.yaml')) @players = %w[Player1 Player2 Player3 Player4 Player5 Player6 Player7 Player8] results = Hash.new players = @players.sort_by{rand} players.each_with_index do |p, i| results[p] = Array[@teams['teir_one'][i]] end second = @players.sort_by{rand} second.each_with_index do |p, i| results[p] << @teams['teir_two'][i] end third = @players.sort_by{rand} third.each_with_index do |p, i| results[p] << @teams['teir_three'][i] end fourth = @players.sort_by{rand} fourth.each_with_index do |p, i| results[p] << @teams['teir_four'][i] end p results I am sure there is a better way to iterate through the tiers, and duplicating the @players object ( dup() or clone() maybe?) So from one Cup Fan to another, help me out.

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  • C++ STL: How to iterate vector while requiring access to element and its index?

    - by Ashwin
    I frequently find myself requiring to iterate over STL vectors. While I am doing this I require access to both the vector element and its index. I used to do this as: typedef std::vector<Foo> FooVec; typedef FooVec::iterator FooVecIter; FooVec fooVec; int index = 0; for (FooVecIter i = fooVec.begin(); i != fooVec.end(); ++i, ++index) { Foo& foo = *i; if (foo.somethingIsTrue()) // True for most elements std::cout << index << ": " << foo << std::endl; } After discovering BOOST_FOREACH, I shortened this to: typedef std::vector<Foo> FooVec; FooVec fooVec; int index = -1; BOOST_FOREACH( Foo& foo, fooVec ) { ++index; if (foo.somethingIsTrue()) // True for most elements std::cout << index << ": " << foo << std::endl; } Is there a better or more elegant way to iterate over STL vectors when both reference to the vector element and its index is required? I am aware of the alternative: for (int i = 0; i < fooVec.size(); ++i) But I keep reading about how it is not a good practice to iterate over STL containers like this.

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  • Rails : can't write unknown attribute `url'

    - by user2954789
    I am new to ruby on rails,and I am learning by creating a blog. I am not able to save to my blogs table and I get this error "can't write unknown attribute url" Blogs migration :db/migrate/ class CreateBlogs < ActiveRecord::Migration --def change --- create_table :blogs do |t| ---- t.string :title ---- t.text :description ---- t.string :slug ---- t.timestamps --- end --end end Blogs Model :/app/models/blogs.rb class Blogs < ActiveRecord::Base --acts_as_url :title --def to_param ---url --end --validates :title, presence:true end Blogs Controller : /app/controllers/blogs_controller.rb class BlogsController < ApplicationController before_action :require_login --def new --- @blogs = Blogs.new --end --def show ---@blogs = Blogs.find(params[:id]) --end --def create ---@blogs = Blogs.new(blogs_params) --if @blogs.save ---flash[:success] = "Your Blog has been created." ---redirect_to home_path --else ---render 'new' --end -end --def blogs_params ---params.require(:blogs).permit(:title,:description) --end private --def require_login ---unless signed_in? ----flash[:error] = "You must be logged in to create a new Blog" ----redirect_to signin_path ---end --end end Blogs Form:/app/views/blogs/new.html.erb Blockquote <%= form_for @blogs, url: blogs_path do |f| %><br/> <%= render 'shared/error_messages_blogs' %><br/> <%= f.label :title %><br/> <%= f.text_field :title %><br/> <%= f.label :description %><br/> <%= f.text_area :description %><br/> <%= f.submit "Submit Blog", class: "btn btn-large btn-primary" %><br/> <% end %><br/> and I have also added "resources :blogs" to my routes.rb file. I get this error in controller at if @blogs.save

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  • Best solution for __autoload

    - by tpk
    As our PHP5 OO application grew (in both size and traffic), we decided to revisit the __autoload() strategy. We always name the file by the class definition it contains, so class Customer would be contained within Customer.php. We used to list the directories in which a file can potentially exist, until the right .php file was found. This is quite inefficient, because you're potentially going through a number of directories which you don't need to, and doing so on every request (thus, making loads of stat() calls). Solutions that come to my mind... -use a naming convention that dictates the directory name (similar to PEAR). Disadvantages: doesn't scale too great, resulting in horrible class names. -come up with some kind of pre-built array of the locations (propel does this for its __autoload). Disadvantage: requires a rebuild before any deploy of new code. -build the array "on the fly" and cache it. This seems to be the best solution, as it allows for any class names and directory structure you want, and is fully flexible in that new files just get added to the list. The concerns are: where to store it and what about deleted/moved files. For storage we chose APC, as it doesn't have the disk I/O overhead. With regards to file deletes, it doesn't matter, as you probably don't wanna require them anywhere anyway. As to moves... that's unresolved (we ignore it as historically it didn't happen very often for us). Any other solutions?

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  • Rails: How do I validate against this code that I put into the lib/ directory?

    - by randombits
    Having a bit of difficulty finding out the proper way to mix in code that I put into the lib/ directory for Rails 2.3.5. I have several models that require phone validation. I had at least three models that used the same code, so I wanted to keep things DRY and moved it out to the lib/ directory. I used to have code like this in each model: validate :phone_is_valid Then I'd have a phone_is_valid method in the model: protected def phone_is_valid # process a bunch of logic errors.add_to_base("invalid phone") if validation failed end I moved this code out into lib/phones/ and in lib/phones I have lib/phones/phone_validation.rb, and in there I copy pasted the phone_is_valid method. My question is, how do I mix this into all of my models now? And does my validate :phone_is_valid method remain the same or does that change? I want to make sure that the errors.add_to_base method continues to function as it did before while keeping everything DRY. I also created another file in lib/phones/ called lib/phones/phone_normalize.rb. Again, many models need the value input by the user to be normalized. Meaning turn (555) 222-1212 to 5552221212 or something similar. Can I invoke that simply by invoking Phones::Phone_Normalize::normalize_method(number)? I suppose I'm confused on the following: How to use the lib directory for validation How to use the lib directory for commonly shared methods that return values

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  • Automatically Organize Tags in Tax/Folksonomy

    - by Rob Wilkerson
    I'm working on a process that will perform natural language processing (NLP) on one--and potentially several--of our content rich sites. What I'd like to do once the NLP is complete is to automatically organize the output (generally a set of terms that you might think of as tags given the prevalence of that metaphor) into some kind of standard or generally accepted organizational structure. In a perfect world, I'd really like this to be crowd sourced under the folksonomy concept (as opposed to a taxonomy) since the ultimate goal is to target/appeal to real people rather than "domain experts", but I'm open to ideas and best practices. For the obvious purpose of scalability, I'd like to automate the population of this tax/folksonomy so that "some guy" in the team/organization isn't responsible for looking at a bunch of words (with or without context) and arbitrarily fleshing out the contextual components of the tree. I have a few ideas for doing this that require some research to establish viability, but I have exactly zero practical experience with this sort of thing so the ideas really just boil down to stuff I made up that might perform some role in accomplishing the task. Imagining that others have vastly more experience with this sort of thing, I'm hoping that I can stand on your shoulders. Thanks for your thoughts and insights.

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  • Java Days & Bookings

    - by sys_debug
    Ok this is an extension of a question I asked about earlier yet this is the next step that is unclear to me. Everything else will be ready and this part is driving me mad! some members provided great help and I already made progress with that info, but this is just another obstacle. I am creating a booking object (as was suggested) that will have a start date and end date. each booking will also have a number of seats associated with it (that I require to reserve). The total available number of seats any given day 46 (as the total capacity of the hall is 46 seats). so in assumption that I have a booking to be made in the system, and start date is 1st jan and end date is 10th jan. The question is how can I check the remaining seats in all those days between the range to see if requested number could be hosted or not? and then when the second booking is made, it will have to see that the days in this range already have less than 46 and decrement further if possible to host the reservation. one of the members, and I appreciate his effort, gladly contributed a method to compare if this booking is after or before the existing bookings. The code provided is here: public boolean overlapsWithExisting(Booking booking) { final Date early = booking.getStart(); final Date late = booking.getEnd(); for(Booking existing : existingBookings) { if(!(early.isAfter(existing.getEnd() || late.isBefore(existing.getStart())) return true; } return false; } I just want to know how to associate 46 with each day and keep record of days that are decremented by bookings. Thanks and reallllllly appreciated :D

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  • How to use Many to Many in Rails?

    - by Newbie
    Hello! In my project, I have users and quests. One User can join multiple quests and one quest can have multiple users. So I created a table called questing, containing the user_id and the quest_id. In my user.rb I did following: require 'digest/sha1' class User < ActiveRecord::Base has_many :questings has_many :quests ,:through =>:questings ... My Quest.rb: class Quest < ActiveRecord::Base has_many :questings has_many :users ,:through =>:questings ... My Questing.rb: class Questing < ActiveRecord::Base belongs_to :quest belongs_to :user end Now I want to create a link or button on my /quests/show.html.erb, calling an action in my controller, which will create the relationship between user and quest. So, in my quest_controller I did: def join_quest @quest = Quest.find(params[:id]) puts '************************' puts 'join quest:' + @quest.id puts '************************' respond_to do |format| format.html { redirect_to(@quest) } format.xml { head :ok } end end and in my show.html.erb I did: <%= link_to 'join this quest!!!', :action => :join_quest %> Now, clicking on this link will cause an error like: Couldn't find Quest with ID=join_quest and the url points to */quests/join_quest* instead of */quests/1/join_quest* Now my questions: Is my quests_controller the right place for my join_quest action, or should I move it to my users_controller? Why do I get this error? How to solve it? What do I have to write in my join_quest action for saving the relationship? On my /users/show.html.erb I want to output all quests the user joined. How to do this? I have to get all this quests from my relationship table, right? How? I hope you can help me! THX!

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  • What's a good way to write batch scripts in C#?

    - by Scott Bilas
    I would like to write simple scripts in C#. Stuff I would normally use .bat or 4NT .btm files for. Copying files, parsing text, asking user input, and so on. Fairly simple but doing this stuff right in a batch file is really hard (no exceptions for example). I'm familiar with command line "scripting" wrappers like AxScript so that gets me part of the way there. What I'm missing is the easy file-manipulation framework. I want to be able to do cd(".."), copy(srcFile, destFile) type functionality. Tools I have tried: NANT, which we use in our build process. Not a good scripting tool. Insanely verbose XML syntax and to add a simple function you must write an extension assembly. Can't do it inline. PowerShell. Looks great, but I just haven't been able to switch over to this as my primary shell. Too many differences from 4NT. Whatever I do needs to run from an ordinary command prompt and not require a special shell to run it through. Can PowerShell be used as a script executor? Perl/Python/Ruby. Really hate learning an entirely new language and framework just to do batch file operations. Haven't been able to dedicate the time I need to do this. Plus, we're a 99% .NET shop for our toolchain and I really want to leverage our existing experience and codebase. Are there frameworks out there that are trying to solve this problem of "make a batch file in C#" that you have used? I want the power of C#/.NET with the immediate-mode type functionality of a typical cmd.exe shell language. Am I alone in wanting something like this?

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  • Regularly update database without browser/user

    - by Chris M
    I currently have a MySQL database which I was hoping to use to store regularly updated data from a temperature sensor connected to the internet. I currently have a page that, when opened, will grab the current temperature and the current timestamp and add it as an entry to the database, but I was looking for a way to do that without me refreshing the page every 5 seconds. Detail: The data comes from an Arduino Ethernet, posted to an IP address. Currently, I'm using cURL to grab the data from the IP, add a timestamp and save it to the DB. Obviously only updates when the page is refreshed (it uses PHP). Here is a live feed of the data - http://wetdreams.org.uk/ChrisProject/UI/live_graph_two.html TL;DR - Basically I need a middle man to grab the data from the IP and post it to a MySQL Edit: Thanks for all the advice. There might be a little bit of confusion, I'm looking for a solution that (ideally) doesn't require a computer to be on at all (other than the Server containing Database). Since I'm looking to store data over long periods of time (weeks), I'd like to set it up and leave a script running on the server (or Arduino) that gets the temp and posts it to the Database. In my head I would like to have a page on the server that automatically (without any browser open, or any other prompting other than a timer) calls a PHP script. Hope that clears things up!

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  • How to translate the fields of a database model?

    - by Tõnis M
    I have some tables/models in a web app that will have multilingual content. For example a university, with it's description in a default language(english) and the user wants he can see the same information in another language( if the object has it's fields translated). If there were only a few languages then I would just add fields like name_en and name_de and so on, but the number of languages isn't fixed, so that' would create a mess. I could also just create a new object with the translated data but then foreign keys wouldn't work, and only some of the fields can be translated so that would create duplicate data. Storing the translations in a file and using gettext or something similar is also not an option since the objects fields can be translated by the website user, not only developers/admins. What would be the best way to design/architect such a database? Searching from the translated data should also be not too complex - as it should not require creating complex joins which would make the queries slower I'm using PostgreSQL and Ruby of Rails but I'm not looking for a technical solution but for a general idea how to design it.

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  • Type-safe generic data structures in plain-old C?

    - by Bradford Larsen
    I have done far more C++ programming than "plain old C" programming. One thing I sorely miss when programming in plain C is type-safe generic data structures, which are provided in C++ via templates. For sake of concreteness, consider a generic singly linked list. In C++, it is a simple matter to define your own template class, and then instantiate it for the types you need. In C, I can think of a few ways of implementing a generic singly linked list: Write the linked list type(s) and supporting procedures once, using void pointers to go around the type system. Write preprocessor macros taking the necessary type names, etc, to generate a type-specific version of the data structure and supporting procedures. Use a more sophisticated, stand-alone tool to generate the code for the types you need. I don't like option 1, as it is subverts the type system, and would likely have worse performance than a specialized type-specific implementation. Using a uniform representation of the data structure for all types, and casting to/from void pointers, so far as I can see, necessitates an indirection that would be avoided by an implementation specialized for the element type. Option 2 doesn't require any extra tools, but it feels somewhat clunky, and could give bad compiler errors when used improperly. Option 3 could give better compiler error messages than option 2, as the specialized data structure code would reside in expanded form that could be opened in an editor and inspected by the programmer (as opposed to code generated by preprocessor macros). However, this option is the most heavyweight, a sort of "poor-man's templates". I have used this approach before, using a simple sed script to specialize a "templated" version of some C code. I would like to program my future "low-level" projects in C rather than C++, but have been frightened by the thought of rewriting common data structures for each specific type. What experience do people have with this issue? Are there good libraries of generic data structures and algorithms in C that do not go with Option 1 (i.e. casting to and from void pointers, which sacrifices type safety and adds a level of indirection)?

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  • multiple models in Rails with a shared interface

    - by dfondente
    I'm not sure of the best structure for a particular situation in Rails. We have several types of workshops. The administration of the workshops is the same regardless of workshop type, so the data for the workshops is in a single model. We collect feedback from participants about the workshops, and the questionnaire is different for each type of workshop. I want to access the feedback about the workshop from the workshop model, but the class of the associated model will depend on the type of workshop. If I was doing this in something other than Rails, I would set up an abstract class for WorkshopFeedback, and then have subclasses for each type of workshop: WorkshopFeedbackOne, WorkshopFeedbackTwo, WorkshopFeedbackThree. I'm unsure how to best handle this with Rails. I currently have: class Workshop < ActiveRecord::Base has_many :workshop_feedbacks end class Feedback < ActiveRecord::Base belongs_to :workshop has_many :feedback_ones has_many :feedback_twos has_many :feedback_threes end class FeedbackOne < ActiveRecord::Base belongs_to :feedback end class FeedbackTwo < ActiveRecord::Base belongs_to :feedback end class FeedbackThree < ActiveRecord::Base belongs_to :feedback end This doesn't seem like to the cleanest way to access the feedback from the workshop model, as accessing the correct feedback will require logic investigating the Workshop type and then choosing, for instance, @workshop.feedback.feedback_one. Is there a better way to handle this situation? Would it be better to use a polymorphic association for feedback? Or maybe using a Module or Mixin for the shared Feedback interface? Note: I am avoiding using Single Table Inheritance here because the FeedbackOne, FeedbackTwo, FeedbackThree models do not share much common data, so I would end up with a large sparsely populated table with STI.

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  • Revision Control System Recommendations

    - by Jordan Arsenault
    I've reached a point in my independent development work where I would like to start using Subversion techniques. Up to now, I've been simply making backups by exporting my current database, and zipping them together with my PHP project files. I've read some articles online and watched a video with Linus Torvalds - the general verdict seems to be that Git is in and old CVS techniques are out. I'm not currently operating under Linux, I do all PHP work out of Windows - Eclipse. Due to the fact that Eclipse runs on JVM, jumping into Linux - Eclipse will be more or less transparent - file system aside. What I would like to accomplish is being able to keep a constant revision history - But I want this to be almost entirely transparent. Also, I work in an MVC framework, and I would like to be able to release my views to Designers, and have them work from within the revision control system too. Will Egit accomplish what I need? Or is it too much overhead for a one-man workforce? What do you recommend I use so that I can keep a revision history? I also require the service to be free! Thank you all - StackOverflow ftw!

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  • Performing an action on Parent/Child elements independently.

    - by Matt Weldon
    I have HTML similar to the following in my page <div id="someDiv"> <img src="foo.gif" class="someImg" /> </div> The wrapper div is set up such that when it is clicked, it's background-color changes using the following jQuery code. $("div").click(function(event){ $(this).css("background-color", "blue"); }); I also have some jQuery associated with my img that will do some other function (for the sake of argument I am going to display and alert box) like so: $("img[class=someImg]").click(function(event){ alert("Image clicked"); }); The issue I have come across is that when I click on the img, the event associated with the div is also triggered. I'm pretty sure that this is due to the way that jQuery (or indeed JavaScript) is handling the two DOM elements - clicking the img would require you to also technically click the div, thus triggering both events. Two questions then really: Is my understanding of the DOM/JavaScript flawed in some way or is this actually how things are occurring? Are there any jQuery methods that would allow me to perform actions on a child element without invoking those associated with its parent?

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  • password-check directive in angularjs

    - by mpm
    I'm writing a password verify directive : Directives.directive("passwordVerify",function(){ return { require:"ngModel", link: function(scope,element,attrs,ctrl){ ctrl.$parsers.unshift(function(viewValue){ var origin = scope.$eval(attrs["passwordVerify"]); if(origin!==viewValue){ ctrl.$setValidity("passwordVerify",false); return undefined; }else{ ctrl.$setValidity("passwordVerify",true); return viewValue; } }); } }; }); html : <input data-ng-model='user.password' type="password" name='password' placeholder='password' required> <input data-ng-model='user.password_verify' type="password" name='confirm_password' placeholder='confirm password' required data-password-verify="user.password"> Given 2 password fields in a form, if both password values are equal then the field affected by the directive is valid. The issue is that it works one way (i.e. when I type a password in the password-verify field). However, when the original password field is updated, the password-verify doesn't become valid. Any idea how I could have a "two way binding verify?"

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