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  • Keeping Computer Science Writing Accessible and Eloquent

    - by Federer
    This question is particularly aimed at descriptions and explanations of what is happening in a computer program, as well as any general advice or approaches for undertaking technical reports in Computer Science at both undergraduate and graduate levels. You see, I am having particular difficulty in the best way to explain what is happening. As in, given any given program from a multi-agent system to a standard webservice, the best and most eloquent way to say exactly what is going on, the logic behind it and it's respective justifications. Should I avoid saying class names? Avoid specifying methods? Keep referring to class variables and any particular references? I'm banging my head against the wall at trying to keep a solid technical foundation and making it accessible to people of all backgrounds. Apologies for the rather vague question. Cheers.

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  • Login or Register (Ruby on rails)

    - by DanielZ
    Hello stackoverflow, I'm working on an Ruby on Rails application (2.3.x) and i want to make a form that lets the user login or register. I want to do this in the same form. I have a JS function that replaces the form elements like this: Login form: <% form_for @user do |f| %> <div id="form"> <%= f.label :email, "E-mail" %> <%= f.text_field :email %> <%= f.label :password, "Password" %> <%= f.password_field :password %> <%= link_to "I don't have an account, "#", :id => "changeForm"%> <%= f.submit "Login" %> </div> <% end %> The id "changeForm" triggers a JS function that changes the form elements. So if you press the url the html looks like this: <% form_for @user do |f| %> <div id="form"> <%= f.label :name, "Name" %> <%= f.text_field :name %> <%= f.label :email, "E-mail" %> <%= f.text_field :email %> <%= f.label :password, "Password" %> <%= f.password_field :password %> <%= f.label :password_confirmation, "Password confirmation" %> <%= f.password_field :password_confirmation %> <%= link_to "I do have an account, "#", :id => "changeForm"%> <%= f.submit "Register" %> </div> <% end %> I added the neccesary validations to my user model: class User < ActiveRecord::Base attr_reader :password validates_presence_of :name, :email, :password validates_format_of :email, :with => /\A([^@\s]+)@((?:[-a-z0-9]+\.)+[a-z]{2,})\Z/i validates_confirmation_of :password But what happens when you fill in the email / password you get the errors that the name is missing and that the password fields aren't confirmed. So i could do some nasty programming in my user model like this: #if password_conf or the name are present the user has tried to register... if params[:user][:password_confirmation].present? || params[:user][:name].present? #so we'll try to save the user if @user.save #if the user is saved authenticate the user current_session.user = User.authenticate(params[:user]) #if the user is logged in? if current_session.user.present? flash[:notice] = "succesvully logged redirect_to some_routes_path else #not logged in... flash[:notice] = "Not logged in" render :action => "new" end else #user not saved render :action => "new" end else #So if the params[:user][:password_confirmation] or [:user][:name] weren't present we geuss the user wants to login... current_session.user = User.authenticate(params[:user]) #are we logged_in? if current_session.user.present? flash[:notice] = "Succesvully logged in" redirect_to some_routes_path else #errors toevoegen @user.errors.add(:email, "The combination of email/password isn't valid") @user.errors.add(:password," ") render :action => "new" end end end Without validations this (imho dirty code and should not be in the controller) works. But i want to use the validates_presence_of methods and i don't want to slap the "conventions over configurations" in the face. So another thing i have tried is adding a hidden field to the form: #login form <%= f.hidden_field :login, :value => true %> # and ofcourse set it to false if we want to register. And then i wanted to use the method: before_validation before_validation_on_create do |user| if params[:user].login == true #throws an error i know... validates_presence_of :email, :password validates_format_of :email, :with => /\A([^@\s]+)@((?:[-a-z0-9]+\.)+[a-z]{2,})\Z/i else validates_presence_of :name, :email, :password validates_format_of :email, :with => /\A([^@\s]+)@((?:[-a-z0-9]+\.)+[a-z]{2,})\Z/i validates_confirmation_of :password end end But this doesn't work because i can't access the params. And login isn't a attribute for the user object. But i thought that in this way i could validate the email and password params if the user wants to login. And all the other attrs if the user want to register. So all i could think of doesn't work how i want it to work. So my main goal is this: 1 form for login/register with the use of the validation methods in the user model. So if we want to login but don't fill in any information = give validation errors. And if the user wants to login but the email/password combination doens't match give the "@user.errors.add(:email, "the combination wasn't found in the db...")". And the same goes for user register... Thanks in advance!

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  • CodeIgniter Validation in Library does not accept callback.

    - by Lukas Oppermann
    Hey guys, my problem is the following: I am writing a login library. This library has a function _validation() and this uses the validation library to validate the data. With using normal validation methods it works just fine, but using a callback function just does not work. It is not called. I call it like this. $this->CI->form_validation->set_rules('user', 'Username', 'required|callback__check_user'); The functions name is _check_user and it uses the username _check_user($user). The function itself works fine and I can also call it in the class ($this-_check_user('username')) with a working result. I am guessing, there might be a problem because I am not workin in a controller so I have a CI instance $this-CI instead of just the original instance $this- Does anyone have a clue how to fix this? Thanks in advance.

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  • How to read and write UTF-8 to disk on the Android?

    - by Rob Kent
    I cannot read and write extended characters (French accented characters, for example) to a text file using the standard InputStreamReader methods shown in the Android API examples. When I read back the file using: InputStreamReader tmp = new InputStreamReader(in); BufferedReader reader = new BufferedReader(tmp); String str; while ((str = reader.readLine()) != null) { ... the string read is truncated at the extended characters instead of at the end-of-line. The second half of the string then comes on the next line. I'm assuming that I need to persist my data as UTF-8 but I cannot find any examples of that, and I'm new to Java. Can anyone provide me with an example or a link to relevant documentation?

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  • Why Aren't Programs Written In Assembly More Often?

    - by mudge
    It seems to be a mainstream opinion that assembly programming takes longer and is more difficult to program in than a higher level language such as C. Therefore it seems to be recommend or assumed that it is better to write in a higher level language for these reasons and for the reason of better portability. Recently I've been writing in x86 assembly and it has dawned on me that perhaps these reasons are not really true, except perhaps portability. Perhaps it is more of a matter of familiarity and knowing how to write assembly well. I also noticed that programming in assembly is quite different than programming in an HLL. Perhaps a good and experienced assembly programmer could write programs just as easily and as quickly as an experienced C programmer writing in C. Perhaps it is because assembly programming is quite different than HLLs, and so requires different thinking, methods and ways, which makes it seem very awkward to program in for the unfamiliar, and so gives it its bad name for writing programs in. If portability isn't an issue, then really, what would C have over a good assembler such as NASM?

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  • Overloading Controller Actions

    - by DaveDev
    Hi Guys I was a bit surprised a few minutes ago when I tried to overload an Action in one of my Controllers I had public ActionResult Get() { return PartialView(/*return all things*/); } I added public ActionResult Get(int id) { return PartialView(/*return 1 thing*/); } .... and all of a sudden neither were working I fixed the issue by making 'id' nullable and getting rid of the other two methods public ActionResult Get(int? id) { if (id.HasValue) return PartialView(/*return 1 thing*/); else return PartialView(/*return everything*/); } and it worked, but my code just got a little bit ugly! Any comments or suggestions? Do I have to live with this blemish on my Controllers? Thanks Dave

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  • Good code architecture for this problem?

    - by RCIX
    I am developing a space shooter game with customizable ships. You can increase the strength of any number of properties of the ship via a pair of radar charts*. Internally, i represent each ship as a subclassed SpaceObject class, which holds a ShipInfo that describes various properties of that ship. I want to develop a relatively simple API that lets me feed in a block of relative strengths (from minimum to maximum of what the radar chart allows) for all of the ship properties (some of which are simplifications of the underlying actual set of properties) and get back a ShipInfo class i can give to a PlayerShip class (that is the object that is instantiated to be a player ship). I can develop the code to do the transformations between simplified and actual properties myself, but i would like some recommendations as to what sort of architecture to provide to minimize the pain of interacting with this translator code (i.e. no methods with 5+ arguments or somesuch other nonsense). Does anyone have any ideas? *=not actually implemented yet, but that's the plan.

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  • (Django) Trim whitespaces from charField

    - by zardon
    How do I strip whitespaces (trim) from the end of a charField in Django? Here is my Model, as you can see I've tried putting in clean methods but these never get run. I've also tried doing name.strip(), models.charField().strip() but these do not work either. Is there a way to force the charField to trim automatically for me? Thanks. class Employee(models.Model): """(Workers, Staff, etc)""" name = models.CharField(blank=True, null=True, max_length=100) # This never gets run def clean_variable(self): data = self.cleaned_data['variable'].strip() return data def __unicode__(self): return self.name class Meta: verbose_name_plural = 'Employees' # This never gets run either class EmployeesForm(forms.ModelForm): class Meta: model = Employee def clean_description(self): #if not self.cleaned_data['description'].strip(): # raise forms.ValidationError('Your error message here') self.cleaned_data['name'].strip()

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  • With the attachment_fu rails plugin, is there any way to delete files uploaded to Amazon S3?

    - by Eric Nguyen
    Let's say I'm using attachment_fu to attach profile pics to user profiles in a system, with Amazon S3 used as the actual file storage. When users upload new profile pics, I'd like to replace the attached file with the new one. I can do this within my database (i.e. the file metadata) easily, but attachment_fu doesn't seem to provide methods for deleting the files from S3. Am I missing something, or am I approaching this the wrong way? Many thanks!

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  • .NET security: how to check if a method is allowed to execute under current user's perrmissions

    - by Gart
    Given an ASP.NET MVC Controller class declaration: public class ItemController : Controller { public ActionResult Index() { // ... } public ActionResult Details() { // ... } [Authorize(Roles="Admin, Editor")] public ActionResult Edit() { // ... } [Authorized(Roles="Admin")] public ActionResult Delete() { // .. } } I need to reflect a list of methods in this class which may be invoked with the current user's permissions. The [Authorized] attribute is specific to ASP.NET MVC, and this is only an example. I would prefer a universal solution for this problem which works for any .NET class. Please share some ideas of what could be done in this case.

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  • Accessing entire netflix catalog via API v1.5

    - by Stone
    Netflix recently updated their API methods for obtaining the full Netflix catalog. I'm curious if anyone has had any success accessing these new xml documents and downloading them via API v1.5 (9/2012). Previously, you could download the entire Netflix catalog via one API call (which I had working perfectly). Now, there are supposedly two calls to make: one for dvd's and one for streaming movies. I cannot make these calls return anything except for an empty array. Please don't offer an answer unless you have personally downloaded the entire catalog via these new API's. Bonus points if you can tell me how to do it in Ruby. http://developer.netflix.com/blog/read/Update_Changes_for_the_Public_API

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  • Text rotation in IE 9

    - by John Bowden
    Hi there I'm attempting to rotate a piece of text on its end within a div using the following different methods. writing-mode: tb-rl; filter: FlipH FlipV; and: -ms-transform: rotate(-90deg); filter: progid:DXImageTransform.Microsoft.Matrix(M11=6.123233995736766e-17, M12=1, M21=-1, M22=6.123233995736766e-17, sizingMethod='auto expand'); Although the text rotates properly in all browsers using either method and even IE all the way up to and including 8. IE 9 produces a horrid pixelated text which is nigh unreadable. Alongside this, IE9 also subtly breaks the layout of various pieces in the application which could be part of the same underlying problem perhaps. If anyone knows a way around this I would be most appreciative. John

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  • Extracting startup errors from Spring contexts

    - by sehugg
    Consider the following output from a Tomcat server under Eclipse: INFO: Initializing Coyote HTTP/1.1 on http-8080 INFO: Initialization processed in 634 ms INFO: Starting service Catalina INFO: Starting Servlet Engine: Apache Tomcat/6.0.20 SEVERE: Error listenerStart SEVERE: Context [/MyServlet] startup failed due to previous errors I would like to figure out what exception caused "Error listenerStart", but Spring seems to be preventing me from finding the error via Eclipse. I'd love to start Catalina manually, but that doesn't seem to do anything. What's the best way to find the hidden exception? I'm not afraid to use torture methods.

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  • What should I do that GWT use <th> instead of <td>?

    - by Paulus
    To build a HTML table I use direct DOM instead of a predefined Widget to set thead and tbody. But when I insert a cell with the insertCell() method GWT inserts an td element but should insert an th element. So TableElement table = Document.get().createTableElement(); TableSectionElement thead = table.createTHead(); TableRowElement headRow = thead.insertRow(-1); headRow.insertCell(-1).setInnerText( "header1" ); gives table/thead/tr/td but should give table/thead/tr/th Any idea how to solve this problem? Use the "old-school" DOM.createXXX()-Methods?

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  • NSArray vs. SQLite for Complex Queries on iPhone

    - by GingerBreadMane
    Developing for iPhone, I have a collection of points that I need to make complex queries on. For example: "How many points have a y-coordinate of 10" and "Return all points with an X-coordinate between 3 and 5 and a y-coordinate of 7". Currently, I am just cycling through each element of an NSArray and checking to see if each element matches my query. It's a pain to write the queries though. SQLite would be much nicer. I'm not sure which would be more efficient though since a SQLite database resides on disk and not in memory (to my understanding). Would SQLite be as efficient or more efficient here? Or is there a better way to do it other than these methods that I haven't thought of? I would need to perform the multiple queries with multiple sets of points thousands of times, so the best performance is important.

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  • What's the best way to avoid try...catch...finally... in my unit tests?

    - by Bruce Li
    I'm writing many unit tests in VS 2010 with Microsoft Test. In each test class I have many test methods similar to below: [TestMethod] public void This_is_a_Test() { try { // do some test here // assert } catch (Exception ex) { // test failed, log error message in my log file and make the test fail } finally { // do some cleanup with different parameters } } When each test method looks like this I fell it's kind of ugly. But so far I haven't found a good solution to make my test code more clean, especially the cleanup code in the finally block. Could someone here give me some advices on this? Thanks in advance.

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  • Error handling and polymorphism

    - by Neeraj
    I have an application with some bunch of code like this: errCode = callMainSystem(); switch (errCode){ case FailErr: error("Err corresponding to val1\n"); case IgnoreErr: error("Err corresponding to val2\n"); ... ... default: error("Unknown error\n"); } The values are enum constants. Will it make some sense to have something like: // Error* callMainSystem() ... Some code return FaileErr(); // or some other error // handling code Error* err = callMainSystem(); err->toString(); The Error class may be made singleton as it only has to print error messages. What are the pros and cons of above methods,size is an important criteria as the application needs to be supported on embedded devices as well. P.S: I don't want to use exception handling because of portability issues and associated overheads.

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  • How do you use Exslt.dyn (especially the 'evaluate' method) in Umbraco?

    - by jeffreypriebe
    I am trying to execute the string contained in an XSL variable. Umbraco has hooks for several Exslt pieces, but it seems the Exslt.dyn (Exslt.dynamic) is not one of them. How do you add it in? Acceptable methods (in order of preference: Writing your own XSLT extension (possibly using existing Umbraco code for Exslt Dynamic). Uploading the XSL from http://www.exslt.org/dyn/functions/evaluate/index.html into Umbraco. Modifying the Umbraco source to add it (possibly using existing Umbraco code for Exslt Dynamic). The reason I mention Exslt Dyanmic is because some Umbraco XSLT sources show a reference that I am assuming existing in some versions of Umbraco. I cannot find it in the source code, however. (Example: the XSL sources pasted in here: http://our.umbraco.org/projects/starter-kits/business-website-starter-pack/general-%28bugs,-feedback,-feature-requests%29/8085-Changing-the-first-day-to-fx-monday)

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  • How to use Sleep in the application in iphone

    - by Pugal Devan
    Hi, I have used to loading a default image in my appication. So i have set to, Sleep(3); in my delegate.m method. But sometimes it will take more than 6 to 7 minutes. So i want to display the image 3 seconds only and then it goes to my appilcation based on my requirements. Which one is best way to do that? Sleep(3) or [NSThread sleepForTimeInterval:3.0] or something else; And i must display the image 3 seconds only. Please explain me. (Note: And I declared setter and getter methods only in my deleagte class.) Please explain me.

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  • Simplest way to extend doctrine for MVC Models

    - by RobertPitt
    Im developing my own framework that uses namespaces. Doctrine is already integrated into my auto loading system and im now at the stage where ill be creating the model system for my application Usually i would create a simple model like so: namespace Application\Models; class Users extends \Framework\Models\Database{} which would inherit all the default database model methods, But with Doctrine im still learning how it all works, as its not just a simple DBAL. I need to understand whats the part of doctrine my classes would extend where i can do the following: namespace Application\Models; class Users Extends Doctrine\Something\Table { public $__table_name = "users"; } And thus within the controller i would be able to do the following: public function Display($uid) { $User = $this->Model->Users->findOne(array("id" => (int)$id)); } Anyone help me get my head around this ?

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  • Why don't I have access to setReadDataOnly() or enableMemoryOptimization() in PHPExcel?

    - by Edward Tanguay
    I've downloaded PHPExcel 1.7.5 Production. I would like to use setReadDataOnly() and enableMemoryOptimization() as discussed in their forum here and in stackoverflow questions. However when I use them, I get a Call to undefined method error. Is there another version or some plugin or library that I have not installed? What do I have to do to access these methods? $objPHPExcel = PHPExcel_IOFactory::load("data/".$file_name); $objPHPExcel->setReadDataOnly(true); //Call to undefined method $objPHPExcel->enableMemoryOptimization(); //Call to undefined method

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  • ASP.Net Web API Routing fails when api is created as a web application under another asp.net site in IIS

    - by neo
    I developed a rest api using ASP.net web api. When I deploy this rest api on iis, I need to create it as a web application under an asp.net web site. When I was deploying the rest api as a new web site in iis, then things worked fine. I was using the following Route api/{controller}/{id}. When I created the rest api as a web application underneath asp.net web site project, I named the web application as api. I can't access the api methods now. Can someone point what I do wrong?

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  • Referencing the current jQuery object in a chain?

    - by Lance McNearney
    At DevDays in SF last year (before jQuery 1.4 was released), I thought they mentioned an upcoming feature in 1.4 that would allow you to reference the current jQuery object while in a chain. I've read through all of the 1.4 improvements and wasn't able to find it. Does anyone know how this can be done? Example Being able to access the current jQuery object would be helpful when working with methods that are in relation to the current object like .next(): // Current way var items = $(this).closest('tr'); items = items.add(items.next(':not([id])')); // Magical 1.4 way? Is there a "chain"-like object? var items = $(this).closest('tr') .add(chain.next(':not([id])'));

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  • Handling multiple async HTTP requests in Silverlight serially

    - by Jeb
    Due to the async nature of http access via WebClient or HttpWebRequest in Silverlight 4, when I want to do multiple http get/posts serially, I find myself writing code that looks like this: doFirstGet(someParams, () => { doSecondGet(someParams, () => { doThirdGet(... } }); Or something similar. I'll end up nesting subsequent calls within callbacks usually implemented using lambdas of some sort. Even if I break things out into Actions or separate methods, it still ends up being hard to read. Does anyone have a clean solution to executing multiple http requests in SL 4 serially? I don't need things to be synchronous, I just want serial execution.

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  • C++ library for Coordinate Transformation Matrices (CTM)?

    - by BastiBense
    I'm looking for a C++ library which allows for easy integration of Coordinate Transformation Matrices (CTM) in my application. You might know CTMs from PDF or PostScript. For one project we are using C++/Qt4 as a framework, which offers a QTransform class, which provides methods like .translate(double x, double y) or .rotate(double degrees). After doing some transformations, it would allow me to get all 6 CTM values, which I could feed into a PDF library or use a transformation matrix in export files. Qt's API also allows for arbitrary mapping of polygons (QPolygon), rectangles (QRect) and other primitive data structures into transformed coordinate systems. So basically I'm looking for something similar to what Qt provides, but without the need of using Qt. I know I could do the matrix multiplications myself, but I'm not really interested in doing so, as I'm very sure that someone already solved this problem, so please no links to books or other guides on how to multiply matrices. Thanks!

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